Updated on 2024/11/19

Information

 

写真a

 
OTSUKA HAJIME
 
Organization
Faculty of Science Department of Physics Assistant Professor
School of Sciences Department of Physics(Concurrent)
Graduate School of Sciences Department of Physics(Concurrent)
Title
Assistant Professor
Contact information
メールアドレス
External link

Research Areas

  • Natural Science / Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics

Degree

  • Doctor of Science

Research History

  • Kyushu University Faculty of Sciences Department of Physics Assistant Professor 

    2022 - Present

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    Country:Japan

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Research Interests・Research Keywords

  • Research theme: String Phenomenology

    Keyword: String phenomenology, String cosmology, Compactifications, Machine learning

    Research period: 2022.1 - Present

Papers

  • Stabilization of a twisted modulus on a mirror of rigid Calabi-Yau manifold

    Keiya Ishiguro, Takafumi Kai, Hajime Otsuka

    Journal of High Energy Physics   2024 ( 10 )   2024.10   ISSN:1029-8479 eISSN:1029-8479

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    Publishing type:Research paper (scientific journal)   Publisher:Journal of High Energy Physics  

    We study the stabilization of a twisted modulus in Type IIB flux compactifications on a mirror of the rigid Calabi-Yau threefold. By analyzing the effective action of twisted and untwisted moduli, we find that three-form fluxes satisfying the tadpole cancellation conditions lead to supersymmetric AdS vacua. We also investigate swampland conjectures on this non-geometric background.

    DOI: 10.1007/JHEP10(2024)060

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  • Spontaneous CP violation and partially broken modular flavor symmetries

    Tetsutaro Higaki, Tatsuo Kobayashi, Kaito Nasu, Hajime Otsuka

    Journal of High Energy Physics   2024 ( 9 )   2024.9   ISSN:1029-8479 eISSN:1029-8479

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    Publishing type:Research paper (scientific journal)   Publisher:Journal of High Energy Physics  

    We study the realization of spontaneous CP violation through moduli stabilization. In modular flavor models, the source of CP violation is the vacuum expectation values of the complex structure moduli of toroidal compact space. We demonstrate that the combined effects of Type IIB flux compactifications with modular invariant couplings between the moduli and matter fields can induce spontaneous CP violation without or with supersymmetry breaking. Furthermore, some general properties of CP and modular invariant scalar potentials are presented. It is found that certain modifications or partial breakings of modular symmetry are useful in generating spontaneous CP violation.

    DOI: 10.1007/JHEP09(2024)024

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  • Nambu-Goldstone modes in magnetized <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>T</mml:mi><mml:mrow><mml:mn>2</mml:mn><mml:mi>n</mml:mi></mml:mrow></mml:msup></mml:math> extra dimensions

    Takuya Hirose, Hajime Otsuka, Koji Tsumura, Yoshiki Uchida

    Physical Review D   110 ( 3 )   2024.8   ISSN:2470-0010 eISSN:2470-0029

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    Publishing type:Research paper (scientific journal)   Publisher:American Physical Society (APS)  

    We consider a U(1) gauge theory on M4×T4 with background magnetic fluxes. We show that a theory including arbitrary fluxes can always be studied in a theory involving only diagonal fluxes by appropriate coordinate transformations. It is found that the number of independent magnetic fluxes is equal to the rank of the classical value of the field strength matrix, rank⟨F⟩. The number of massless zero modes induced from extra components of higher-dimensional gauge field (Wilson-line scalar field) is also determined by rank⟨F⟩. We explicitly confirm that the quantum corrections due to the matter fermion to the squared mass of the Wilson-line scalar field cancel out at the one-loop level. For this purpose, we derive the fermion mass spectrum on M4×T4 with arbitrary fluxes. By taking the flux diagonal basis, creation and annihilation operators for Kaluza-Klein quantum numbers are defined appropriately. Our results are easily generalized to the case of M4×T2n(n≥3).

    Published by the American Physical Society 2024

    DOI: 10.1103/physrevd.110.035032

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    Other Link: http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevD.110.035032/fulltext

  • Autoencoder-driven clustering of intersecting D-brane models via tadpole charge

    Keiya Ishiguro, Satsuki Nishimura, Hajime Otsuka

    Journal of High Energy Physics   2024 ( 8 )   2024.8   ISSN:1029-8479 eISSN:1029-8479

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    Publishing type:Research paper (scientific journal)   Publisher:Journal of High Energy Physics  

    We study the well-known type IIA intersecting D-brane models on the T6/ℤ2×ℤ2′ orientifold via a machine-learning approach. We apply several autoencoder models with and without positional encoding to D6-brane configurations satisfying certain concrete models described in ref. [1] and attempt to extract some features which the configurations possess. We observe that the configurations cluster in two-dimensional latent layers of the autoencoder models and analyze which physical quantities are relevant to the clustering. As a result, it is found that tadpole charges of hidden D6-branes characterize the clustering. We expect that there is another important factor because a checkerboard pattern in two-dimensional latent layers is observed in the clustering.

    DOI: 10.1007/JHEP08(2024)133

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  • Modular forms and hierarchical Yukawa couplings in heterotic Calabi-Yau compactifications

    Keiya Ishiguro, Tatsuo Kobayashi, Satsuki Nishimura, Hajime Otsuka

    Journal of High Energy Physics   2024 ( 8 )   2024.8   ISSN:1029-8479 eISSN:1029-8479

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    Publishing type:Research paper (scientific journal)   Publisher:Journal of High Energy Physics  

    We study the modular symmetry in heterotic string theory on Calabi-Yau threefolds. In particular, we examine whether moduli-dependent holomorphic Yukawa couplings are described by modular forms in the context of heterotic string theory with standard embedding. We find that SL(2, ℤ) modular symmetry emerges in asymptotic regions of the Calabi-Yau moduli space. The instanton-corrected holomorphic Yukawa couplings are then given by modular forms under SL(2, ℤ) or its congruence subgroups such as Γ0(3) and Γ0(4). In addition to the modular symmetry, it turns out that another coupling selection rule controls the structure of holomorphic Yukawa couplings. Furthermore, the coexistence of both the positive and negative modular weights for matter fields leads to a hierarchical structure of matter field Kähler metric. Thus, these holomorphic modular forms and the matter field Kähler metric play an important role in realizing a hierarchical structure of physical Yukawa couplings.

    DOI: 10.1007/JHEP08(2024)088

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  • Stringy constraints on primordial electromagnetic fields in axion inflation

    Hajime Otsuka, Ryo Yokokura

    Journal of High Energy Physics   2024 ( 7 )   2024.7   ISSN:1029-8479 eISSN:1029-8479

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    Publishing type:Research paper (scientific journal)   Publisher:Journal of High Energy Physics  

    We study primordial electromagnetic fields in effective actions of string theory. In contrast to a conventional scenario of producing primordial electromagnetic fields induced by the axion inflation, we deal with the Dirac-Born-Infeld action as a non-linear generation of Maxwell theory. It turns out that the intensity of generated electromagnetic fields is bounded from above by the string scale which can also be rewritten in terms of supersymmetry breaking scale in the context of type IIB Large Volume Scenario. The instability parameter ξ is constrained by the tadpole cancellation condition of D3-branes and a realization of hierarchy between the string scale and the Hubble scale of inflation. Hence, the magnetogenesis can be realized in the limited corner of the string landscape due to the O(1) value of the coefficient of Chern-Simons coupling.

    DOI: 10.1007/JHEP07(2024)055

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  • Texture zeros realization in a three-loop radiative neutrino mass model from modular A<inf>4</inf> symmetry

    Takaaki Nomura, Hiroshi Okada, Hajime Otsuka

    Nuclear Physics B   1004   2024.7   ISSN:0550-3213 eISSN:1873-1562

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    Publishing type:Research paper (scientific journal)   Publisher:Nuclear Physics B  

    We derive verifiable two-zero textures in the framework of a three-loop induced neutrino mass model applying a modular A4 symmetry for the lepton sector. Interestingly, the neutrino mass structure is determined by assignments of the right-handed charged-lepton particles only. We show all the possible texture patterns and demonstrate their analytical and numerical analyses. Finally, we mention a possibility of detection for doubly-charged boson via colliders that decays into specific modes due to the flavor symmetry.

    DOI: 10.1016/j.nuclphysb.2024.116579

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  • Induced moduli oscillation by radiation and space expansion in a higher-dimensional model

    Hajime Otsuka, Yutaka Sakamura

    Physical Review D   109 ( 11 )   2024.6   ISSN:2470-0010 eISSN:2470-0029

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    Publishing type:Research paper (scientific journal)   Publisher:Physical Review D  

    We investigate the cosmological expansion of the 3D space in a 6D model compactified on a sphere, beyond the 4D effective theory analysis. We focus on a case where the initial temperature is higher than the compactification scale. In such a case, the pressure for the compact space affects the moduli dynamics and induces the moduli oscillation even if they are stabilized at the initial time. Under some plausible assumptions, we derive the explicit expressions for the 3D scale factor and the moduli background in terms of analytic functions. Using them, we evaluate the transition times between different cosmological eras as functions of the model parameters and the initial temperature.

    DOI: 10.1103/PhysRevD.109.115019

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  • Flux Landscape with enhanced symmetry not on SL(2, ℤ) elliptic points

    Keiya Ishiguro, Takafumi Kai, Tatsuo Kobayashi, Hajime Otsuka

    Journal of High Energy Physics   2024 ( 2 )   2024.2   ISSN:1029-8479 eISSN:1029-8479

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    Language:Others   Publishing type:Research paper (scientific journal)   Publisher:Journal of High Energy Physics  

    We study structures of solutions for SUSY Minkowski F-term equations on two toroidal orientifolds with h2,1 = 1. Following our previous study [1], with fixed upper bounds of a flux D3-brane charge Nflux, we obtain a whole Landscape and a distribution of degeneracies of physically-distinct solutions for each case. In contrast to our previous study, we consider a non-factorizable toroidal orientifold and its Landscape on which SL(2, ℤ) is violated into a certain congruence subgroup, as it had been known in past studies. We find that it is not the entire duality group that a complex-structure modulus U enjoys but its outer semi-direct product with a “scaling” outer automorphism group. The fundamental region is enlarged to include the |U| < 1 region. In addition, we find that high degeneracy is observed at an elliptic point, not of SL(2, Z) but of the outer automorphism group. Furthermore, ℤ2-enhanced symmetry is realized on the elliptic point. The outer automorphism group is exceptional in the sense that it is consistent with a symplectic basis transformation of background three-cycles, as opposed to the outer automorphism group of SL(2, ℤ). We also compare this result with Landscape of another factorizable toroidal orientifold.

    DOI: 10.1007/JHEP02(2024)099

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  • Modular flavor models with positive modular weights: a new lepton model building

    Tatsuo Kobayashi, Takaaki Nomura, Hiroshi Okada, Hajime Otsuka

    Journal of High Energy Physics   2024 ( 1 )   2024.1   ISSN:1029-8479 eISSN:1029-8479

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    Language:Others   Publishing type:Research paper (scientific journal)   Publisher:Journal of High Energy Physics  

    We propose an interesting assignment of positive modular weights for fields in a modular non-Abelian discrete flavor symmetry. By this assignment, we can construct inverse seesaw and linear seesaw models without any additional symmetries which possess good testability in current experiments. At first, we discuss possibilities for positive modular weights from a theoretical point of view. Then we show concrete examples of inverse seesaw and linear seesaw scenarios applying modular A 4 symmetry as examples and demonstrate some predictions as well as consistency with experimental results such as neutrino masses and mixings.

    DOI: 10.1007/JHEP01(2024)121

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  • Upper bound on the Atiyah-Singer index from tadpole cancellation

    Keiya Ishiguro, Takafumi Kai, Satsuki Nishimura, Hajime Otsuka, Maki Takeuchi

    Journal of High Energy Physics   2024 ( 1 )   2024.1   ISSN:1029-8479 eISSN:1029-8479

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    We propose an upper bound on the Atiyah-Singer index in the effective action of string theory. For E 8 × E8′ and SO(32) heterotic string theories on smooth Calabi-Yau threefolds with line bundles, we find that the tadpole cancellation and supersymmetry conditions lead to an upper bound on the generation number of quarks and leptons as well as Higgs doublets. By taking into account the observed value of four-dimensional gauge couplings and the supergravity approximation, we explicitly evaluate the bound on favorable complete intersection Calabi-Yau threefolds. The bound can be extended to Calabi-Yau threefolds in the Kreuzer-Skarke database. We also put the upper bound on the Atiyah-Singer index in Type IIB/F-theory compactifications.

    DOI: 10.1007/JHEP01(2024)200

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  • Sequestered string models imply split supersymmetry

    Michele Cicoli, Alessandro Cotellucci, Hajime Otsuka

    Journal of High Energy Physics   2024 ( 1 )   2024.1   ISSN:1029-8479 eISSN:1029-8479

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    Language:Others   Publishing type:Research paper (scientific journal)   Publisher:Journal of High Energy Physics  

    Sequestering is a promising mechanism in 4D string models to reconcile high-scale inflation with low-energy supersymmetry. In this scenario the MSSM lives on branes at singularities and it is sequestered from the sources of supersymmetry breaking in the bulk. The soft-terms are suppressed with respect to the gravitino mass so that all moduli are heavy enough to avoid any cosmological moduli problem. In this paper we study stability bounds and flavour constraints on sequestered string models, finding that they can be satisfied if the soft-terms give rise to a mass spectrum typical of split supersymmetry with TeV-scale gauginos and sfermions around 107 GeV. When instead scalar and gaugino masses are of the same order of magnitude, large flavour changing neutral currents can be avoided only by pushing the soft-terms above 106 GeV. However this scenario is in tension with stability bounds due to the presence of charge and colour breaking vacua which could be populated in the early universe, and the possible emergence of directions along which the potential is unbounded from below.

    DOI: 10.1007/JHEP01(2024)059

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  • Development of Reinforcement-Learning Based Search Strategy in Theoretical Particle Physics

    NISHIMURA Satsuki, MIYAO Coh, OTSUKA Hajime

    Proceedings of the Annual Conference of JSAI   JSAI2024 ( 0 )   1F4GS1003 - 1F4GS1003   2024   eISSN:27587347

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    Language:Japanese   Publisher:The Japanese Society for Artificial Intelligence  

    <p>In theoretical particle physics, various hypothetical models are proposed to explain unsolved problems of particle phenomena. To validate them exhaustively, theoretical predictions should be compared with experimental data. However, the parameter space is large in general, so it is difficult to analyze the models numerically with low cost. In this work considering such a situation, we focus on matter particles that are called as quarks and leptons, and improve a method to explore their flavor structure with reinforcement learning. We utilize Deep Q-Network for one kind of the models, and train neural networks on the integer charges of quarks and leptons. The results show that there are indeed solutions that reproduce the experimental and renormalized masses of the quarks and leptons. On the other hand, the results suggest that appropriate parameters are very scarce when considering domain-wall problems, which are severely constrained by cosmological observations. Given its usefulness for such analysis, we expect that reinforcement learning can be applied to the verification of realistic particle models.</p>

    DOI: 10.11517/pjsai.jsai2024.0_1f4gs1003

    CiNii Research

  • Exploring the flavor structure of quarks and leptons with reinforcement learning

    Satsuki Nishimura, Coh Miyao, Hajime Otsuka

    Journal of High Energy Physics   2023 ( 12 )   2023.12   ISSN:1029-8479 eISSN:1029-8479

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    Language:Others   Publishing type:Research paper (scientific journal)   Publisher:Journal of High Energy Physics  

    We propose a method to explore the flavor structure of quarks and leptons with reinforcement learning. As a concrete model, we utilize a basic value-based algorithm for models with U(1) flavor symmetry. By training neural networks on the U(1) charges of quarks and leptons, the agent finds 21 models to be consistent with experimentally measured masses and mixing angles of quarks and leptons. In particular, an intrinsic value of normal ordering tends to be larger than that of inverted ordering, and the normal ordering is well fitted with the current experimental data in contrast to the inverted ordering. A specific value of effective mass for the neutrinoless double beta decay and a sizable leptonic CP violation induced by an angular component of flavon field are predicted by autonomous behavior of the agent. Our finding results indicate that the reinforcement learning can be a new method for understanding the flavor structure.

    DOI: 10.1007/JHEP12(2023)021

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  • Flavor, CP and metaplectic modular symmetries in Type IIB chiral flux vacua

    Keiya Ishiguro, Takafumi Kai, Hiroshi Okada, Hajime Otsuka

    Journal of High Energy Physics   2023 ( 12 )   2023.12   ISSN:1029-8479 eISSN:1029-8479

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    We examine symmetries of chiral four-dimensional vacua of Type IIB flux compactifications with vanishing superpotential W = 0. We find that the N = 1 supersymmetric MSSM-like and Pati-Salam vacua possess enhanced discrete symmetries in the effective action below the mass scale of stabilized complex structure moduli and dilaton. Furthermore, a generation number of quarks/leptons is small on these vacua where the flavor, CP and metaplectic modular symmetries are described in the framework of eclectic flavor symmetry.

    DOI: 10.1007/JHEP12(2023)136

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  • Moduli inflation from modular flavor symmetries

    Yoshihiko Abe, Tetsutaro Higaki, Fumiya Kaneko, Tatsuo Kobayashi, Hajime Otsuka

    Journal of High Energy Physics   2023 ( 6 )   2023.7   ISSN:1029-8479 eISSN:1029-8479

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:SPRINGER  

    We study slow-roll inflation model controlled by the modular flavor symmetry.
    In the model, the modulus field plays a role of inflaton and the introduction
    of the stabilizer field coupled to a modular form in the superpotential
    produces the inflaton potential. In order to generate the flat direction for
    the slow-roll inflation, we consider the K\"{a}hler potential corrected by the
    modular form. It is noted that the modulus field perpendicular to the inflaton
    direction is stabilized during the inflation. The model is turns out to be
    consistent with the current observations and behaves similarly to the
    $\alpha$-attractor models in some parameter spaces. The inflaton rolls down to
    the CP-symmetric vacuum at the end of inflation.

    DOI: 10.1007/JHEP06(2023)187

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    Other Link: http://arxiv.org/pdf/2303.02947v1

  • Full higher-dimensional analysis of moduli oscillation and radiation in expanding universe

    Hajime Otsuka, Yutaka Sakamura

    Journal of High Energy Physics   2023 ( 5 )   2023.6   ISSN:1029-8479 eISSN:1029-8479

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:SPRINGER  

    We investigate effects of the radiation and the moduli oscillation around the
    stabilized values on the evolution of a 6-dimensional spacetime compactified on
    $S^2$. In order to see the transition from the 5-dimensional space to the
    3-dimensional one, we develop a procedure to pursue the spacetime evolution
    with appropriate approximations, which is valid until the spacetime behaves
    like 4-dimensional. In the case that the moduli stabilization process cannot be
    described in the context of the 4-dimensional effective theory, it takes quite
    a long time for the moduli oscillation to dominate the total energy density, in
    contrast to the conventional result obtained by the 4-dimensional effective
    theory approach. We also found that even if the moduli are set at the
    stabilized values, they start to oscillate due to the pressure in the extra
    space $S^2$ in some cases.

    DOI: 10.1007/JHEP05(2023)231

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    Other Link: http://arxiv.org/pdf/2212.14314v1

  • Generalized matter parities from finite modular symmetries

    Tatsuo Kobayashi, Satsuki Nishimura, Hajime Otsuka, Morimitsu Tanimoto, Kei Yamamoto

    PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS   2023 ( 4 )   2023.4   ISSN:2050-3911

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:OXFORD UNIV PRESS INC  

    We classify a supersymmetric extension of the Standard Model by discrete symmetries originating from finite modular symmetries Gamma(N). Since all the couplings in supersymmetric theories of finite modular symmetries Gamma(N) are described by holomorphic modular forms with even modular weights, renormalizable and non-renormalizable operators such as baryon- and/or lepton-number violating operators are severely constrained. From the modular transformation of matter multiplets with modular weight 1/M, we find Z(2M) symmetries, including the generalized baryon and lepton parities, R-parity, Z(3) baryon triality and Z(6) proton hexality. Such Z(2M) symmetries are enlarged to Z(2M) (sic) Z(2)(CP) symmetries together with the CP transformation.

    DOI: 10.1093/ptep/ptad041

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  • Index theorem on magnetized blow-up manifold of T2/ ZN

    Tatsuo Kobayashi, Hajime Otsuka, Makoto Sakamoto, Maki Takeuchi, Yoshiyuki Tatsuta, Hikaru Uchida

    Physical Review D   107 ( 7 )   2023.4   ISSN:2470-0010 eISSN:2470-0029

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    We investigate blow-up manifolds of T2=7LN(N = 2; 3; 4; 6) orbifolds with magnetic flux. First, we construct the blow-up manifolds and zero-mode wave functions on them more precisely. In particular, through an appropriate singular gauge transformation, winding numbers of wave functions on T2=7LN can be replaced with localized curvature and localized flux at orbifold fixed points. In addition, since the blow-up manifolds have no singularities, we apply the Atiyah-Singer index theorem to them; the chiral zero-mode number is given by the total magnetic flux. It can be also applied for T2=7LN orbifolds through the blow-up process, and then we find that it is consistent with the zero-mode counting formula in M. Sakamoto et al. [Zero-mode counting formula and zeros in orbifold compactifications, Phys. Rev. D 102, 025008 (2020).]. Furthermore, the Atiyah-Singer index theorem shows that an additional degree of freedom of localized flux gives new chiral zero modes. We study their wave functions and then we find that they correspond to localized modes at the orbifold singular points. We also calculate their Yukawa couplings.

    DOI: 10.1103/PhysRevD.107.075032

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  • Remark on modular weights in low-energy effective field theory from type II string theory

    Shota Kikuchi, Tatsuo Kobayashi, Kaito Nasu, Hajime Otsuka, Shohei Takada, Hikaru Uchida

    Journal of High Energy Physics   2023 ( 4 )   2023.4   ISSN:1029-8479 eISSN:1029-8479

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    We revisit the modular weights in type IIB magnetized D-brane models. The simple analysis of wave function shows that the four-dimensional matter fields have the modular weight -1/2, but it may shift as one in type IIA intersecting D-brane models. For example, the localized gauge flux as well as the localized curvature can shift the modular weight in the magnetized D-brane models. Such corrections do not affect physical couplings such as physical Yukawa couplings. However, it leads to differences in supersymmetry breaking sfermion masses, which depend on the modular weights, although the A-term coefficients and the sum of sfermion masses squared seem to be the same between two models.

    DOI: 10.1007/JHEP04(2023)003

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  • Phenomenological implications on a hidden sector from the festina lente bound

    Kayoung Ban, Dhong Yeon Cheong, Hiroshi Okada, Hajime Otsuka, Jong Chul Park, Seong Chan Park

    Progress of Theoretical and Experimental Physics   2023 ( 1 )   2023.1   ISSN:2050-3911 eISSN:2050-3911

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    Language:Others   Publishing type:Research paper (scientific journal)   Publisher:Progress of Theoretical and Experimental Physics  

    We apply the Festina Lente (FL) bound on a hidden sector with $U(1)$ gauge
    symmetries. Since the FL bound puts a lower bound on masses of particles
    charged under the $U(1)$ gauge symmetries, it is possible to constrain the
    hidden sector even with a tiny coupling to the Standard Model. In particular,
    we focus on the phenomenological implications of the FL bound on milli-charged
    particles, which naturally arise when kinetic mixing between the photon and the
    hidden photon is allowed. It turns out that the milli-charged particle with the
    mass $M\lesssim 5$ meV is prohibited by the FL bound in the case of a single
    hidden $U(1)$, independent of the value of kinetic mixing. This bound is
    crucial when bosonic dark matter is taken in consideration in this framework:
    the fuzzy bosonic dark matter models requesting minuscule masses are ruled out
    by the FL bound if the longevity of dark matter is protected by the hidden
    gauge symmetry.

    DOI: 10.1093/ptep/ptac176

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    Other Link: http://arxiv.org/pdf/2206.00890v1

  • Pseudo-Nambu-Goldstone dark matter from non-Abelian gauge symmetry

    Hajime Otsuka, Takashi Shimomura, Koji Tsumura, Yoshiki Uchida, Naoki Yamatsu

    Physical Review D   106 ( 11 )   2022.12   ISSN:2470-0010 eISSN:2470-0029

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    Language:Others   Publishing type:Research paper (scientific journal)   Publisher:Physical Review D  

    We propose a pseudo-Nambu-Goldstone boson (pNGB) dark matter (DM) model based on an additional non-Abelian gauge symmetry SU(2)D. The gauge symmetry SU(2)D is spontaneously broken to a global custodial symmetry U(1)V via the nonvanishing vacuum expectation values of SU(2)D doublet and triplet scalar fields. Due to the exact global symmetry U(1)V, the lightest U(1)V charged particle becomes stable. We assume that the lightest charged particle in the model is the charged complex pNGB, which we regard as DM. It avoids the strong constraints from current DM direct detection experiments due to the property of NGB. We find that the measured energy density of DM can be reproduced when the DM mass is larger than the half of the Higgs mass, where the lower limit generally comes from the constraint of DM invisible decay and the upper limit from DM direct detection experiments depends on the model parameters.

    DOI: 10.1103/PhysRevD.106.115033

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  • Modular symmetry of soft supersymmetry breaking terms

    Shota Kikuchi, Tatsuo Kobayashi, Kaito Nasu, Hajime Otsuka, Shohei Takada, Hikaru Uchida

    PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS   2022 ( 12 )   2022.12   ISSN:2050-3911

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:OXFORD UNIV PRESS INC  

    We study the modular symmetry of soft supersymmetry breaking terms. Soft scalar masses and A-term coefficients are invariant under the modular symmetry when we regard the F-term as a spurion with the modular weight -2. Their flavor structure is determined by the same symmetry as Yukawa couplings, i.e., fermion masses. The modular symmetric behavior of the mu-term and B-term depends on how the mu-term is generated.

    DOI: 10.1093/ptep/ptac152

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  • Zero-mode wave functions by localized gauge fluxes

    Tatsuo Kobayashi, Hajime Otsuka, Makoto Sakamoto, Maki Takeuchi, Yoshiyuki Tatsuta, Hikaru Uchida

    2022.11

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    We study chiral zero-mode wave functions on blow-up manifolds of $T^2/Z_N$
    orbifolds with both bulk and localized magnetic flux backgrounds. We introduce
    a singular gauge transformation in order to remove $Z_N$ phases for $Z_N$
    twisted boundary condition of matter fields. We compute wave functions of not
    only bulk zero modes but also localized modes at the orbifold singular points,
    which correspond to new zero modes induced by localized flux. By studying their
    Yukawa couplings, it turns out that only three patterns of Yukawa couplings are
    allowed. Our theory has a specific coupling selection rule.

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    Other Link: http://arxiv.org/pdf/2211.04596v1

  • Zero-mode wave functions by localized gauge fluxes

    Tatsuo Kobayashi, Hajime Otsuka, Makoto Sakamoto, Maki Takeuchi, Yoshiyuki Tatsuta, Hikaru Uchida

    2022.11

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    We study chiral zero-mode wave functions on blow-up manifolds of $T^2/Z_N$
    orbifolds with both bulk and localized magnetic flux backgrounds. We introduce
    a singular gauge transformation in order to remove $Z_N$ phases for $Z_N$
    twisted boundary condition of matter fields. We compute wave functions of not
    only bulk zero modes but also localized modes at the orbifold singular points,
    which correspond to new zero modes induced by localized flux. By studying their
    Yukawa couplings, it turns out that only three patterns of Yukawa couplings are
    allowed. Our theory has a specific coupling selection rule.

  • Residual flavor symmetry breaking in the landscape of modular flavor models

    Keiya Ishiguro, Hiroshi Okada, Hajime Otsuka

    Journal of High Energy Physics   2022 ( 9 )   2022.9   ISSN:1029-8479

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    We study a symmetry breaking of residual flavor symmetries realized at fixed
    points of the moduli space. In the supersymmetric modular invariant theories, a
    small departure of the modulus from fixed points is required to realize fermion
    mass hierarchies and sizable CP-breaking effects. We investigate whether one
    can dynamically fix the moduli values in the vicinity of the fixed points in
    the context of Type IIB string theory. It is found that the string landscape
    prefers $|\delta \tau| \simeq 10^{-5}$ for the deviation of the complex
    structure modulus from all fixed points and the CP-breaking vacuum is
    statistically favored. To illustrate phenomenological implications of
    distributions of moduli values around fixed points, we analyze the lepton
    sector on a concrete $A_4$ modular flavor model.

    DOI: 10.1007/JHEP09(2022)072

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  • 4D modular flavor symmetric models inspired by a higher-dimensional theory

    Shota Kikuchi, Tatsuo Kobayashi, Hajime Otsuka, Morimitsu Tanimoto, Hikaru Uchida, Kei Yamamoto

    Physical Review D   106 ( 3 )   2022.8   ISSN:2470-0010 eISSN:2470-0029

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    We study a scenario to derive four-dimensional modular flavor symmetric
    models from higher dimensional theory by assuming the compactification
    consistent with the modular symmetry. In our scenario, wavefunctions in extra
    dimensional compact space are modular forms. That leads to constraints on
    combinations between modular weights and $\Gamma_N$ ($\Gamma_N')$
    representations of matter fields. We also present illustrating examples.

    DOI: 10.1103/PhysRevD.106.035001

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    Other Link: http://arxiv.org/pdf/2201.04505v1

  • Spacetime evolution during moduli stabilization in radiation dominated era beyond 4D effective theory

    Hajime Otsuka, Yutaka Sakamura

    Journal of High Energy Physics   08 ( 8 )   120 - 120   2022.8   ISSN:1029-8479

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    We investigate the time evolution of the background spacetime during the
    moduli stabilization process, which is assumed to occur in the radiation
    dominated era. The setup is basically the Salam-Sezgin model, but we add a
    potential term for the dilaton in order to stabilize the moduli completely. We
    numerically solve the higher-dimensional background field equations, including
    a case that the stabilization process cannot be described within the 4D
    effective theory. In contrast to the conventional 4D effective theory analysis,
    we find that when the mass scale of the stabilization is larger than the
    compactification scale, the radiation contribution to the total energy density
    remains to be non-negligible for a much longer time than the stabilization time
    scale. As a result, the non-compact 3D space expands slower than the matter
    dominated universe. We also find the equation of state for the
    radiation~$w_{\rm rad}$ remains to be smaller than 1/3 for a long time, which
    indicates that the radiation still feels the extra dimensions for a while even
    after the moduli are stabilized.

    DOI: 10.1007/JHEP08(2022)120

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    Other Link: http://arxiv.org/pdf/2205.00175v1

  • Lepton flavor violation, lepton (g − 2)$_{μ, e}$ and electron EDM in the modular symmetry

    Tatsuo Kobayashi, Hajime Otsuka, Morimitsu Tanimoto, Kei Yamamoto

    Journal of High Energy Physics   08 ( 8 )   013 - 013   2022.8   ISSN:1029-8479

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    We study the lepton flavor violation (LFV), the leptonic magnetic moments
    $(g-2)_{\mu,\,e} $ and the electric dipole moment (EDM) of the electron in the
    Standard-Model Effective Field Theory with the $\Gamma_N$ modular flavor
    symmetry. We employ the stringy Ansatz on coupling structure that 4-point
    couplings of matter fields are written by a product of 3-point couplings of
    matter fields. We take the level 3 finite modular group, $\Gamma_3$ for the
    flavor symmetry, and discuss the dipole operators at nearby fixed point
    $\tau=i$, where observed lepton masses and mixing angles are well reproduced.
    Suppose the anomaly of the anomalous magnetic moment of the muon to be evidence
    of the new physics (NP), we have related it with $(g-2)_{e}$, LFV decays, and
    the electron EDM. It is found that the NP contribution to $(g-2)_{e}$ is
    proportional to the lepton masses squared likewise the naive scaling. We also
    discuss the correlations among the LFV processes $\mu\to e\gamma$, $\tau\to
    \mu\gamma$ and $\tau\to e\gamma$, which are testable in the future. The
    electron EDM requires the tiny imaginary part of the relevant Wilson
    coefficient in the basis of real positive charged lepton masses, which is
    related to the $\mu\to e\gamma$ transition in our framework.

    DOI: 10.1007/JHEP08(2022)013

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    Other Link: http://arxiv.org/pdf/2204.12325v1

  • Modular symmetry in the SMEFT

    Tatsuo Kobayashi, Hajime Otsuka, Morimitsu Tanimoto, Kei Yamamoto

    Physical Review D   105 ( 5 )   2022.3   ISSN:2470-0010 eISSN:2470-0029

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    We study the modular symmetric standard-model effective field theory. We
    employ the stringy Ansatz on coupling structure that 4-point couplings
    $y^{(4)}$ of matter fields are written by a product of 3-point couplings
    $y^{(3)}$ of matter fields, i.e., $y^{(4)} = y^{(3)}y^{(3)}$. In this
    framework, we discuss the flavor structure of bilinear fermion operators and
    4-fermion operators, where the holomorphic and anti-holomorphic modular forms
    appear. From the Ansatz, the $A_4$ modular-invariant semileptonic four-fermion
    operator $[\,\bar E_R \Gamma E_R][\,\bar D_R \Gamma D_R\,]$ does not lead to
    the flavor changing (FC) processes since this operator would be constructed in
    terms of gauge couplings $g$ as $y^{(3)} \sim g$. The chirality flipped
    bilinear operator $[\,\bar D_R \Gamma D_L\,]$ also does not lead FC if the
    mediated mode corresponds to the Higgs boson $H_d$. In this case, the flavor
    structure of this operator is the exactly same as the mass matrix. On the other
    hand, if the flavor structure of the operator is not the exactly same as the
    mass matrix, the situation would change drastically. Then, we obtain the
    non-trivial relations of FC transitions at nearby fixed points
    $\tau=i,\,\omega\,, i\infty$, which are testable in the future. As an
    application, we discuss the relations of the lepton flavor violation processes
    $ \mu\to e\gamma,\, \tau\to \mu\gamma$ and $\tau\to e\gamma$ at nearby
    $\tau_e=i$, where the successful lepton mass matrix was obtained. We also study
    the flavor changing 4-quark operators in the $A_4$ modular symmetry of quarks.
    As a result, the minimal flavor violation could be realized by taking relevant
    specific parameter sets of order one.

    DOI: 10.1103/PhysRevD.105.055022

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    Other Link: http://arxiv.org/pdf/2112.00493v2

  • Radiative neutrino masses from modular $A_4$ symmetry and supersymmetry breaking

    Hajime Otsuka, Hiroshi Okada

    2022.2

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    We investigate a modular $A_4$ invariant two-loop neutrino mass model in a
    supersymmetric framework, where we introduce new fields as minimum as possible,
    expecting contributions of superpartners to the neutrino masses. We
    successfully reproduce the neutrino oscillation data thanks to the superpartner
    contributions in case of normal hierarchy, and predict several observables such
    as phases and neutrino masses, concentrating on three specific regions at
    nearby fixed points of modulus $ au=i,omega,i imes infty$, where
    $omegaequiv e^{2pi i/3}$. These points are statistically favored in flux
    compactifications of the string theory. We show several results in each the
    points by performing global $chi^2$ analysis, and demonstrate benchmark points
    with the minimum $chi^2$.

  • On stringy origin of minimal flavor violation

    Tatsuo Kobayashi, Hajime Otsuka

    European Physical Journal C   82 ( 1 )   2022.1   ISSN:1434-6044 eISSN:1434-6052

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    We study the minimal flavor violation in the context of string effective
    field theory. Stringy selection rules indicate that $n$-point couplings among
    fermionic zero-modes and lightest scalar modes in the string effective action
    are given by a product of Yukawa couplings which are regarded as spurion fields
    of stringy and geometrical symmetries. Hence, Yukawa couplings determine the
    dynamics of flavor and CP violations. This observation strongly supports the
    hypothesis of minimal flavor violation in the Standard Model effective field
    theory.

    DOI: 10.1140/epjc/s10052-022-09986-4

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    Other Link: http://arxiv.org/pdf/2108.02700v2

  • Symplectic modular symmetry in heterotic string vacua: flavor, CP, and R-symmetries

    Keiya Ishiguro, Tatsuo Kobayashi, Hajime Otsuka

    Journal of High Energy Physics   2022 ( 1 )   2022.1   eISSN:1029-8479

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    We examine a common origin of four-dimensional flavor, CP, and $U(1)_R$
    symmetries in the context of heterotic string theory with standard embedding.
    We find that flavor and $U(1)_R$ symmetries are unified into the $Sp(2h+2,
    \mathbb{C})$ modular symmetries of Calabi-Yau threefolds with $h$ being the
    number of moduli fields. Together with the $\mathbb{Z}_2^{\rm CP}$ CP symmetry,
    they are enhanced to $GSp(2h+2, \mathbb{C})\simeq Sp(2h+2, \mathbb{C})\rtimes
    \mathbb{Z}_2^{\rm CP}$ generalized symplectic modular symmetry. We exemplify
    the $S_3, S_4, T^\prime, S_9$ non-Abelian flavor symmetries on explicit
    toroidal orbifolds with and without resolutions and $\mathbb{Z}_2,S_4$ flavor
    symmetries on three-parameter examples of Calabi-Yau threefolds. Thus,
    non-trivial flavor symmetries appear in not only the exact orbifold limit but
    also a certain class of Calabi-Yau threefolds. These flavor symmetries are
    further enlarged to non-Abelian discrete groups by the CP symmetry.

    DOI: 10.1007/JHEP01(2022)020

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  • Sharpening the boundaries between flux landscape and swampland by tadpole charge

    Keiya Ishiguro, Hajime Otsuka

    Journal of High Energy Physics   2021 ( 12 )   2021.12

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    We investigate the vacuum structure of four-dimensional effective theory
    arising from Type IIB flux compactifications on a mirror of the rigid
    Calabi-Yau threefold, corresponding to a T-dual of the
    DeWolfe-Giryavets-Kachru-Taylor model in Type IIA flux compactifications. By
    analyzing the vacuum structure of this interesting corner of string landscape,
    it turns out that there exist perturbatively unstable de Sitter (dS) vacua in
    addition to supersymmetric and non-supersymmetric anti-de Sitter vacua. On the
    other hand, the stable dS vacua appearing in the low-energy effective action
    violate the tadpole cancellation condition, indicating a strong correlation
    between the existence of dS vacua and the flux-induced D3-brane charge (tadpole
    charge). We also find analytically that the tadpole charge constrained by the
    tadpole cancellation condition emerges in the scalar potential in a nontrivial
    way. Thus, the tadpole charge would restrict the existence of stable dS vacua,
    and this fact underlies the statement of the dS conjecture. Furthermore, our
    analytical and numerical results exhibit that distributions of ${cal O}(1)$
    parameters in expressions of several swampland conjectures peak at specific
    values.

    DOI: 10.1007/JHEP12(2021)017

  • Spontaneous CP violation and symplectic modular symmetry in Calabi-Yau compactifications

    Keiya Ishiguro, Tatsuo Kobayashi, Hajime Otsuka

    Nuclear Physics B   973   2021.12

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    We explore the geometrical origin of CP and the spontaneous CP violation in
    Calabi-Yau compactifications. We find that the CP symmetry is identified with
    an outer automorphism of the symplectic modular group in the large complex
    structure regime of Calabi-Yau threefolds, thereby enlarging the symplectic
    modular group to their semidirect product group. The spontaneous CP violation
    is realized by the introduction of fluxes, whose effective action is invariant
    under CP as well as the discrete $mathbb{Z}_2$ symmetry or $mathbb{Z}_4$
    R-symmetry. We explicitly demonstrate the spontaneous CP violation on a
    specific Calabi-Yau threefold.

    DOI: 10.1016/j.nuclphysb.2021.115598

  • Hierarchical structure of physical Yukawa couplings from matter field Kähler metric

    Keiya Ishiguro, Tatsuo Kobayashi, Hajime Otsuka

    Journal of High Energy Physics   2021 ( 7 )   2021.3

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    We study the impacts of matter field K"ahler metric on physical Yukawa
    couplings in string compactifications. Since the K"ahler metric is non-trivial
    in general, the kinetic mixing of matter fields opens a new avenue for
    realizing a hierarchical structure of physical Yukawa couplings, even when
    holomorphic Yukawa couplings have the trivial structure. The hierarchical
    Yukawa couplings are demonstrated by couplings of pure untwisted modes on
    toroidal orbifolds and their resolutions in the context of heterotic string
    theory with standard embedding. Also, we study the hierarchical couplings among
    untwisted and twisted modes on resolved orbifolds.

    DOI: 10.1007/JHEP07(2021)064

  • Landscape of modular symmetric flavor models

    Keiya Ishiguro, Tatsuo Kobayashi, Hajime Otsuka

    Journal of High Energy Physics   2021 ( 3 )   2021.3

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    <jats:title>A<jats:sc>bstract</jats:sc>
    </jats:title><jats:p>We study the moduli stabilization from the viewpoint of modular flavor symmetries. We systematically analyze stabilized moduli values in possible configurations of flux compactifications, investigating probabilities of moduli values and showing which moduli values are favorable from our moduli stabilization. Then, we examine their implications on modular symmetric flavor models. It is found that distributions of complex structure modulus <jats:italic>τ</jats:italic> determining the flavor structure are clustered at a fixed point with the residual ℤ<jats:sub>3</jats:sub> symmetry in the SL(2<jats:italic>,</jats:italic> ℤ) fundamental region. Also, they are clustered at other specific points such as intersecting points between <jats:italic>|</jats:italic><jats:italic>τ</jats:italic><jats:italic>|</jats:italic><jats:sup>2</jats:sup> = <jats:italic>k/</jats:italic>2 and Re <jats:italic>τ</jats:italic> = 0<jats:italic>,</jats:italic><jats:italic>±</jats:italic>1<jats:italic>/</jats:italic>4<jats:italic>,</jats:italic><jats:italic>±</jats:italic>1<jats:italic>/</jats:italic>2, although their probabilities are less than the ℤ<jats:sub>3</jats:sub> fixed point. In general, CP-breaking vacua in the complex structure modulus are statistically disfavored in the string landscape. Among CP-breaking vacua, the values Re <jats:italic>τ</jats:italic> = <jats:italic>±</jats:italic>1<jats:italic>/</jats:italic>4 are most favorable in particular when the axio-dilaton <jats:italic>S</jats:italic> is stabilized at Re <jats:italic>S</jats:italic> = <jats:italic>±</jats:italic>1<jats:italic>/</jats:italic>4. That shows a strong correlation between CP phases originated from string moduli.</jats:p>

    DOI: 10.1007/jhep03(2021)161

  • Small flux superpotential in F-theory compactifications

    Yoshinori Honma, Hajime Otsuka

    Physical Review D   103 ( 12 )   2021.3

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    We investigate whether a class of models describing F-theory
    compactifications admits a specific type of flux vacua with an exponentially
    small vacuum expectation value of the superpotential, by generalizing a method
    recently developed in Type IIB flux compactifications. First we clarify that a
    restricted choice of $G_4$-flux components reduces a general flux
    superpotential into a simple form, which promotes the existence of
    supersymmetric vacua with one flat direction at the perturbative level. Then we
    utilize the techniques of mirror symmetry to determine one-instanton
    corrections to the potential and investigate in detail the vacuum solutions of
    a particular model.

    DOI: 10.1103/PhysRevD.103.126022

  • Modular symmetry by orbifolding magnetized T 2 × T 2: realization of double cover of Γ<inf> N</inf>

    Shota Kikuchi, Tatsuo Kobayashi, Hajime Otsuka, Shintaro Takada, Hikaru Uchida

    Journal of High Energy Physics   2020 ( 11 )   2020.11

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    We study the modular symmetry of zero-modes on $T_1^2 imes T_2^2$ and
    orbifold compactifications with magnetic fluxes, $M_1,M_2$, where modulus
    parameters are identified. This identification breaks the modular symmetry of
    $T^2_1 imes T^2_2$, $SL(2,mathbb{Z})_1 imes SL(2,mathbb{Z})_2$ to
    $SL(2,mathbb{Z})equivGamma$. Each of the wavefunctions on $T^2_1 imes
    T^2_2$ and orbifolds behaves as the modular forms of weight 1 for the principal
    congruence subgroup $Gamma$($N$), $N$ being 2 times the least common multiple
    of $M_1$ and $M_2$. Then, zero-modes transform each other under the modular
    symmetry as multiplets of double covering groups of $Gamma_N$ such as the
    double cover of $S_4$.

    DOI: 10.1007/JHEP11(2020)101

  • Common origin of the strong CP and CKM phases in string compactifications

    Tatsuo Kobayashi, Hajime Otsuka

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics   807   2020.8

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    We explore the scenario where both the strong CP and
    Cabbibo-Kobayashi-Maskawa (CKM) phases are determined by the same axion field.
    Such a scenario is naturally realized in string compactifications. We find that
    there exists parameter region to realize the tiny strong CP phase and observed
    CKM phase in magnetized D-brane models.

    DOI: 10.1016/j.physletb.2020.135554

  • Challenge for spontaneous CP violation in Type IIB orientifolds with fluxes

    Tatsuo Kobayashi, Hajime Otsuka

    Physical Review D   102 ( 2 )   2020.7

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    We systematically investigate possibilities of realizing the spontaneous CP
    violation in Type IIB flux compactifications on toroidal orientifolds. Our
    detailed analysis leads to the presence of flat directions at degenerate
    CP-breaking and -conserving vacua for a generic choice of three-form fluxes,
    indicating that flux compactifications are not sufficient to realize the
    spontaneous CP violation. Furthermore, the four-dimensional CP can be embedded
    into the duality symmetries, namely modular symmetries for a particular choice
    of fluxes.

    DOI: 10.1103/PhysRevD.102.026004

  • Classification of discrete modular symmetries in type IIB flux vacua

    Tatsuo Kobayashi, Hajime Otsuka

    Physical Review D   101 ( 10 )   2020.5

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    We classify discrete modular symmetries in the effective action of Type IIB
    string on toroidal orientifolds with three-form fluxes, emphasizing on
    $T^6/mathbb{Z}_2$ and $T^6/(mathbb{Z}_2 imes mathbb{Z}_2^prime)$
    orientifold backgrounds. On the three-form flux background, the modular group
    is spontaneously broken down to its congruence subgroup whose pattern is
    severely constrained by a quantization of fluxes and tadpole cancellation
    conditions. We explicitly demonstrate that the congruence subgroups appearing
    in the effective action arise on magnetized D-branes wrapping certain cycles of
    tori.

    DOI: 10.1103/PhysRevD.101.106017

  • Deep learning and k-means clustering in heterotic string vacua with line bundles

    Hajime Otsuka, Kenta Takemoto

    Journal of High Energy Physics   2020 ( 5 )   2020.5

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    We apply deep-learning techniques to the string landscape, in particular,
    $SO(32)$ heterotic string theory on simply-connected Calabi-Yau threefolds with
    line bundles. It turns out that three-generation models cluster in particular
    islands specified by deep autoencoder networks and k-means++ clustering.
    Especially, we explore mutual relations between model parameters and the
    cluster with densest three-generation models (called "3-generation island"). We
    find that the 3-generation island has a strong correlation with the topological
    data of Calabi-Yau threefolds, in particular, second Chern class of the tangent
    bundle of the Calabi-Yau threefolds. Our results also predict a large number of
    Higgs pairs in the 3-generation island.

    DOI: 10.1007/JHEP05(2020)047

  • F-theory flux vacua and attractor equations

    Yoshinori Honma, Hajime Otsuka

    Journal of High Energy Physics   2020 ( 4 )   2020.4

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    We examine the vacuum structure of 4D effective theories of moduli fields in
    spacetime compactifications with quantized background fluxes. Imposing the
    no-scale structure for the volume deformations, we numerically investigate the
    distributions of flux vacua of the effective potential in complex structure
    moduli and axio-dilaton directions for two explicit examples in Type IIB string
    theory and F-theory compactifications. It turns out that distributions of
    non-supersymmetric flux vacua exhibit a non-increasing functional behavior of
    several on-shell quantities with respect to the string coupling. We point out
    that this phenomena can be deeply connected with a previously-reported possible
    correspondence between the flux vacua in moduli stabilization problem and the
    attractor mechanism in supergravity, and our explicit demonstration implies
    that such a correspondence generically exist even in the framework of F-theory.
    In particular, we confirm that the solutions of the effective potential we
    explicitly evaluated in Type IIB and F-theory flux compactifications indeed
    satisfy the generalized form of the attractor equations simultaneously.

    DOI: 10.1007/JHEP04(2020)001

  • Flavor structure of magnetized T 2 /ℤ<inf>2</inf> blow-up models

    Tatsuo Kobayashi, Hajime Otsuka, Hikaru Uchida

    Journal of High Energy Physics   2020 ( 3 )   2020.3

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    We discuss the flavor structure in a resolutions of magnetized
    $T^2/mathbb{Z}_2$ orbifold models. The flavor structure of Yukawa couplings
    among chiral zero-modes is sensitive to radii of the resolved fixed points of
    $T^2/mathbb{Z}_2$ orbifold. We show in concrete models that the realistic mass
    hierarchy and mixing angles of the quark sector can be realized at certain
    values of blow-up radii, where the number of parameters in the blow-up model
    can be smaller than toroidal orbifold one.

    DOI: 10.1007/JHEP03(2020)042

  • Unitary matrix with a Penner-like potential also yields N<inf>f</inf> = 2

    Shun'ya Mizoguchi, Hajime Otsuka, Hitomi Tashiro

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics   800   2020.1

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    It has been known for some time that a hermitian matrix model with a
    Penner-like potential yields as its large-N free energy the prepotential of N=2
    N_f=2 SU(2) SUSY gauge theory. We give a rigorous proof that a unitary matrix
    model with the identical potential also yields the same prepotential, although
    the parameter identifications are slightly different. This result has been
    anticipated by Itoyama et. al.

    DOI: 10.1016/j.physletb.2019.135075

  • Wavefunctions and Yukawa couplings on resolutions of T2/ℤ<inf>N</inf> orbifolds

    Tatsuo Kobayashi, Hajime Otsuka, Hikaru Uchida

    Journal of High Energy Physics   2019 ( 8 )   2019.8

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    We propose matter wavefunctions on resolutions of $T^2/mathbb{Z}_N$
    singularities with constant magnetic fluxes. In the blow-down limit, the
    obtained wavefunctions of chiral zero-modes result in those on the magnetized
    $T^2/mathbb{Z}_N$ orbifold models, but the wavefunctions of
    $mathbb{Z}_N$-invariant zero-modes receive the blow-up effects around fixed
    points of $T^2/mathbb{Z}_N$ orbifolds. Such blow-up effects change the
    selection rules and Yukawa couplings among the chiral zero-modes as well as the
    modular symmetry, in contrast to those on the magnetized $T^2/mathbb{Z}_N$
    orbifold models.

    DOI: 10.1007/JHEP08(2019)046

  • Zero-mode product expansions and higher-order couplings in gauge backgrounds

    Masaki Honda, Tatsuo Kobayashi, Hajime Otsuka

    PHYSICAL REVIEW D   100 ( 2 )   2019.7

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    We study a four-dimensional low-energy effective field theory derived from extradimensional field theories with flux backgrounds. We find that products among fermionic zero modes and lightest scalar modes are expanded by other fermionic zero modes and lightest scalar modes. Using this aspect, we show that higher-order couplings among the fermionic zero modes and the lightest scalar mode can be decomposed into three-point couplings. This selection rule, originating from a structure of the Dirac-type operators, indicates the operator product expansion in the underlying conformal field theory.

    DOI: 10.1103/PhysRevD.100.025015

  • Heterotic stringy corrections to metrics of toroidal orbifolds and their resolutions

    Pompey Leung, Hajime Otsuka

    Physical Review D   99 ( 12 )   2019.6

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    We explicitly analyse $O(alpha')$ corrections to heterotic supergravity on
    toroidal orbifolds and their resolutions, which play important roles in string
    phenomenology as well as moduli stabilisation. Using a conformal factor ansatz
    that is valid only for four dimensional geometries, we obtain a closed
    expression for the $O(alpha')$ metric corrections in the case of several
    orbifold limits of K3, namely $T^4/mathbb{Z}_n$ where $n=2,3,4,6$. However, we
    find that non-standard embedding requires the inclusion of five-branes on such
    orbifolds. We also numerically investigate the behaviour around orbifold fixed
    points by considering the metric correction on the resolution of a
    $mathbb{C}^2/mathbb{Z}_2$ singularity. In this case, a non-trivial conformal
    factor can be obtained in non-standard embedding even without five-branes. In
    the same manner, we generalise our analysis to study metric corrections on
    $T^6/mathbb{Z}_3$ and its resolution described by a complex line bundle over
    $mathbb{CP}^2$. Further prospects of utilising these $O(alpha')$ corrected
    metrics as a novel approach in obtaining realistic or semi-realistic Yukawa
    couplings are discussed.

    DOI: 10.1103/PhysRevD.99.126011

  • Affleck-Dine baryogenesis in the SUSY Dine-Fischler-Srednicki-Zhitnitsky axion model without R parity

    Kensuke Akita, Hajime Otsuka

    Physical Review D   99 ( 5 )   2019.3

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    We investigate the baryon asymmetry in the supersymmetry
    Dine-Fischler-Srednicki-Zhitnitsky axion model without R-parity. It turns out
    that the R-parity violating terms economically explain the atmospheric
    mass-squared difference of neutrinos and the appropriate amount of baryon
    asymmetry through the Affleck-Dine mechanism. In this model, the axion is a
    promising candidate for the dark matter and the axion isocurvature perturbation
    is suppressed due to the large field values of Peccei-Quinn fields. Remarkably,
    in some parameter regions explaining the baryon asymmetry and the axion dark
    matter abundance, the proton decay will be explored in future experiments.

    DOI: 10.1103/PhysRevD.99.055035

  • SO(32) heterotic standard model vacua in general Calabi-Yau compactifications

    Hajime Otsuka, Kenta Takemoto

    Journal of High Energy Physics   2018 ( 11 )   2018.11

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    We study a direct flux breaking scenario in $SO(32)$ heterotic string theory
    on general Calabi-Yau threefolds. The direct flux breaking, corresponding to
    hypercharge flux breaking in the F-theory context, allows us to derive the
    Standard Model in general Calabi-Yau compactifications. We present a general
    formula leading to the three generations of quarks and leptons and no chiral
    exotics in a background-independent way. As a concrete example, we show the
    three-generation model on a complete intersection Calabi-Yau threefold.

    DOI: 10.1007/JHEP11(2018)034

  • SO(32) heterotic line bundle models

    Hajime Otsuka

    Journal of High Energy Physics   2018 ( 5 )   2018.5

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    We search for the three-generation standard-like and/or Pati-Salam models
    from the $SO(32)$ heterotic string theory on smooth, quotient complete
    intersection Calabi-Yau threefolds with multiple line bundles, each with
    structure group $U(1)$. These models are S- and T-dual to intersecting D-brane
    models in type IIA string theory. We find that the stable line bundles and
    Wilson lines lead to the standard model gauge group with an extra $U(1)_{B-L}$
    via a Pati-Salam-like symmetry and the obtained spectrum consists of three
    chiral generations of quarks and leptons, and vector-like particles.
    Green-Schwarz anomalous U(1) symmetries control not only the Yukawa couplings
    of the quarks and leptons but also the higher-dimensional operators causing the
    proton decay.

    DOI: 10.1007/JHEP05(2018)045

  • Radiative Kähler moduli stabilization

    Tatsuo Kobayashi, Naoya Omoto, Hajime Otsuka, Takuya H. Tatsuishi

    Physical Review D   97 ( 10 )   2018.5

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    DOI: 10.1103/physrevd.97.106006

  • On the flux vacua in F-theory compactifications

    Yoshinori Honma, Hajime Otsuka

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics   774   225 - 228   2017.11

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    We study moduli stabilization of the F-theory compactified on an elliptically fibered Calabi-Yau fourfold. Our setup is based on the mirror symmetry framework including brane deformations. The complex structure moduli dependence of the resulting 4D N = 1 effective theory is determined by the associated fourfold period integrals. By turning on appropriate G-fluxes, we explicitly demonstrate that all the complex structure moduli fields can be stabilized around the large complex structure point of the F-theory fourfold. (c) 2017 The Author(s). Published by Elsevier B.V.

    DOI: 10.1016/j.physletb.2017.09.062

  • Supersymmetry preserving and breaking degenerate vacua, and radiative moduli stabilization

    Tatsuo Kobayashi, Naoya Omoto, Hajime Otsuka, Takuya H. Tatsuishi

    Physical Review D   96 ( 4 )   2017.8

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    We propose a new type of moduli stabilization scenario where the supersymmetric and supersymmetry-breaking minima are degenerate at the leading level. The inclusion of the loop corrections originating from the matter fields resolves this degeneracy of vacua. Light axions are predicted in one of our models.

    DOI: 10.1103/PhysRevD.96.046004

  • Axion inflation and Affleck-Dine baryogenesis

    Kensuke Akita, Tatsuo Kobayashi, Hajime Otsuka

    Journal of Cosmology and Astroparticle Physics   2017 ( 4 )   2017.4

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    String theory generically predicts the coupling between the Affleck-Dine field and axion field through higher-dimensional operators. We thus explore the Affleck-Dine baryogenesis on an axion background. It turns out that the axion oscillation produces an enough amount of baryon asymmetry of the Universe just after the inflation, even without a soft supersymmetry-breaking A-term. This baryogenesis scenario is applicable to the string axion inflation.

    DOI: 10.1088/1475-7516/2017/04/042

  • Constraints on small-field axion inflation

    Tatsuo Kobayashi, Akane Oikawa, Naoya Omoto, Hajime Otsuka, Ikumi Saga

    Physical Review D   95 ( 6 )   2017.3

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    We study general class of small-field axion inflations, which are the mixture of polynomial and sinusoidal functions suggested by the natural and axion monodromy inflations. The axion decay constants leading to the successful axion inflations are severely constrained in order not to spoil the big bang nucleosynthesis and overproduce the isocurvature perturbation originating from the QCD axion. We in turn find that the cosmologically favorable axion decay constants are typically of order the grand unification scale or the string scale, which is consistent with the prediction of closed-string axions.

    DOI: 10.1103/PhysRevD.95.063514

  • Axion decay constants at special points in type II string theory Reviewed

    Masaki Honda, Akane Oikawa, Hajime Otsuka

    Journal of High Energy Physics   2017 ( 1 )   064   2017.1

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    We propose the mechanism to disentangle the decay constant of closed string axion from the string scale in the framework of type II string theory on Calabi-Yau manifold. We find that the quantum and geometrical corrections in the prepotential that arise at some special points in the moduli space widen the window of axion decay constant. In particular, around the small complex structure points, the axion decay constant becomes significantly lower than the string scale. We also discuss the moduli stabilization leading to the phenomenologically attractive low-scale axion decay constant.

    DOI: 10.1007/JHEP01(2017)064

  • Flavor structure in so (32) heterotic string theory

    Hiroyuki Abe, Tatsuo Kobayashi, Hajime Otsuka, Yasufumi Takano, Takuya H. Tatsuishi

    Physical Review D   94 ( 12 )   2016.12

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    We study the flavor structure in SO(32) heterotic string theory on six-dimensional tori with magnetic fluxes. Specifically, we focus on models with the flavor symmetries SU(3)(f) and Delta(27). In both models, we can realize the realistic quark masses and mixing angles.

    DOI: 10.1103/PhysRevD.94.126020

  • Small field axion inflation with sub-Planckian decay constant Reviewed

    Kenji Kadota, Tatsuo Kobayashi, Akane Oikawa, Naoya Omoto, Hajime Otsuka, Takuya H. Tatsuishi

    Journal of Cosmology and Astroparticle Physics   2016 ( 10 )   013   2016.10

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    We study an axion inflation model recently proposed within the framework of type IIB superstring theory, where we pay a particular attention to a sub-Planckian axion decay constant. Our axion potential can lead to the small field inflation with a small tensor-to-scalar ratio, and a typical reheating temperature can be as low as GeV.

    DOI: 10.1088/1475-7516/2016/10/013

  • Wavefunctions on magnetized branes in the conifold

    Hiroyuki Abe, Akane Oikawa, Hajime Otsuka

    Journal of High Energy Physics   2016 ( 7 )   2016.7

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    We study wavefunctions on D7-branes with magnetic fluxes in the conifold. Since some supersymmetric embeddings of D- branes on the AdS(5) x T-1,T-1 geometry are known, we consider one of the embeddings, especially the spacetime filling D7-branes in which (a part of) the standard model is expected to be realized. The explicit form of induced metric on the D7-branes allows us to solve the Laplace and Dirac equations to evaluate matter wavefunctions in extra dimensions analytically. We find that the zeromode wavefunctions can be localized depending on the configuration of magnetic fluxes on D7-branes, and show some phenomenological aspects.

    DOI: 10.1007/JHEP07(2016)054

  • Gauge coupling unification in SO(32) heterotic string theory with magnetic fluxes Reviewed

    Hiroyuki Abe, Tatsuo Kobayashi, Hajime Otsuka, Yasufumi Takano, Takuya H. Tatsuishi

    Progress of Theoretical and Experimental Physics   2016 ( 5 )   2016.5

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    We study SO(32) heterotic string theory on a torus with magnetic fluxes. Non-vanishing fluxes can lead to non-universal gauge kinetic functions for SU(3) x SU(2) x U(1)gamma, which is an important feature of SO(32) heterotic string theory in contrast to the E-8 x E-8 theory. It is found that the experimental values of gauge couplings are realized with O(1) values of moduli fields based on realistic models with the SU(3) x SU(2) x U(1)gamma gauge symmetry and three chiral generations of quarks and leptons without chiral exotics.

    DOI: 10.1093/ptep/ptw038

  • Moduli mediation without moduli-induced gravitino problem

    Kensuke Akita, Tatsuo Kobayashi, Akane Oikawa, Hajime Otsuka

    Journal of High Energy Physics   2016 ( 5 )   2016.5

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    Abstract: We study the moduli-induced gravitino problem within the framework of the phenomenologically attractive mirage mediations. The huge amount of gravitino generated by the moduli decay can be successfully diluted by introducing an extra light modulus field which does not induce the supersymmetry breaking. Since the lifetime of extra modulus field becomes longer than usually considered modulus field, our proposed mechanism is applied to both the low- and high-scale supersymmetry breaking scenarios. We also point out that such an extra modulus field appears in the flux compactification of type II string theory.

    DOI: 10.1007/JHEP05(2016)178

  • New potentials for string axion inflation

    Kobayashi, Tatsuo, Oikawa, Akane, Otsuka, Hajime

    Physical Review D - Particles, Fields, Gravitation and Cosmology   93 ( 8 )   2016.4

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    New potentials for string axion inflation
    © 2016 American Physical Society.We propose a new type of axion inflation with complex structure moduli in the framework of type IIB superstring theory compactified on the Calabi-Yau manifold. The inflaton is identified as the axion for the complex structure moduli whose potential is originating from instantonic corrections appearing through the period vector of the mirror Calabi-Yau manifold. The axionic shift symmetry is broken down to the discrete one by the inclusion of the instantonic correction and certain three-form fluxes. Our proposed inflation scenario is compatible with Kähler moduli stabilization. We also study a typical reheating temperature in the case of complex structure moduli inflation.

    DOI: 10.1103/PhysRevD.93.083508

  • Axion inflation with cross-correlated axion isocurvature perturbations

    Kenji Kadota, Tatsuo Kobayashi, Hajime Otsuka

    Journal of Cosmology and Astroparticle Physics   2016 ( 1 )   2016.1

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    We study the inflation scenarios, in the framework of superstring theory, where the inflaton is an axion producing the adiabatic curvature perturbations while there exists another light, axion producing the isocurvature perturbations. We discuss how the non-trivial couplings among string axions can generically arise, and calculate the consequent cross-correlations between the adiabatic and isocurvature modes through concrete examples. Based on the Planck analysis on the generally correlated isocurvature perturbations, we show that there is a preference for the existence of the correlated isocurvature modes for the axion monodromy inflation while the natural inflation disfavors such isocurvature modes.

    DOI: 10.1088/1475-7516/2016/01/044

  • Particle physics and cosmology with high-scale SUSY breaking in five-dimensional supergravity models

    Hajime Otsuka

    Journal of High Energy Physics   2015 ( 10 )   2015.10

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    Abstract: We discuss a high-scale SUSY breaking scenario with the wino dark matter in the five-dimensional supergravity model on S&lt
    sup&gt
    1&lt
    /sup&gt
    /Z&lt
    inf&gt
    2&lt
    /inf&gt
    . The extra U(1) symmetries broken by the orbifold projection control the flavor structure of soft SUSY-breaking parameters as well as the Yukawa couplings, and a scalar component of the one of moduli multiplets, which arise from extra-dimensional components of the U(1) vector multiplets, induces the slow-roll inflation. Because of the supersymmetric moduli stabilization as well as the moduli inflation, it is found that the correct dark matter relic abundance is non-thermally generated by the gravitino decaying into the wino.

    DOI: 10.1007/JHEP10(2015)008

  • Realistic three-generation models from SO(32) heterotic string theory

    Hiroyuki Abe, Tatsuo Kobayashi, Hajime Otsuka, Yasufumi Takano

    Journal of High Energy Physics   2015 ( 9 )   2015.9

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    Abstract: We search for realistic supersymmetric standard-like models from SO(32) heterotic string theory on factorizable tori with multiple magnetic fluxes. Three chiral ganerations of quarks and leptons are derived from the adjoint and vector representations of SO(12) gauge groups embedded in SO(32) adjoint representation. Massless spectra of our models also include Higgs fields, which have desired Yukawa couplings to quarks and leptons at the tree-level.

    DOI: 10.1007/JHEP09(2015)056

  • Moduli stabilization to a natural MSSM with gravitino dark matter and inflation

    Hajime Otsuka

    Physical Review D - Particles, Fields, Gravitation and Cosmology   92 ( 4 )   2015.8

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    We propose the gravitino dark matter in the gravity mediated supersymmetry breaking scenario. The mass hierarchies between the gravitino and other superparticles can be achieved by the nontrivial Kähler metric of the supersymmetry breaking field. As a concrete model, we consider the five-dimensional supergravity model in which moduli are stabilized, and then one of the moduli induces the slow-roll inflation. It is found that the relic abundance of the gravitino and the Higgs boson mass reside in the allowed range without a severe fine-tuning.

    DOI: 10.1103/PhysRevD.92.045001

  • Towards natural inflation from weakly coupled heterotic string theory Reviewed

    Hiroyuki Abe, Tatsuo Kobayashi, Hajime Otsuka

    Progress of Theoretical and Experimental Physics   2015 ( 6 )   2015.6

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    We propose natural inflation from the heterotic string theory on the "Swiss-Cheese" Calabi-Yau manifold with multiple U(1) magnetic fluxes. Such multiple U(1) magnetic fluxes stabilize the same number of the linear combination of the universal axion and Kahler axions, and one of the Kahler axions is identified as the inflaton. This axion decay constant can be determined by the size of one-loop corrections to the gauge kinetic function of the hidden gauge groups, which leads effectively to the trans-Planckian axion decay constant consistent with the Planck data. During the inflation, the real parts of the moduli are also stabilized by employing the nature of the "Swiss-Cheese" Calabi-Yau manifold.

    DOI: 10.1093/ptep/ptv075

  • Natural inflation with and without modulations in type IIB string theory Reviewed

    Hiroyuki Abe, Tatsuo Kobayashi, Hajime Otsuka

    Journal of High Energy Physics   2015 ( 4 )   2015.4

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    We propose a mechanism for the natural inflation with and without modulation in the framework of type IIB string theory on toroidal orientifold or orbifold. We explicitly construct the stabilization potential of complex structure, dilaton and Kahler moduli, where one of the imaginary component of complex structure moduli becomes light which is identified as the inflaton. The inflaton potential is generated by the gaugino-condensation term which receives the one-loop threshold corrections determined by the field value of complex structure moduli and the axion decay constant of inflaton is enhanced by the inverse of one-loop factor. We also find the threshold corrections can also induce the modulations to the original scalar potential for the natural inflation. Depending on these modulations, we can predict several sizes of tensor-to-scalar ratio as well as the other cosmological observables reported by WMAP, Planck and/or BICEP2 collaborations.

    DOI: 10.1007/JHEP04(2015)160

  • Moduli inflation in five-dimensional supergravity models Reviewed

    Hiroyuki Abe, Hajime Otsuka

    Journal of Cosmology and Astroparticle Physics   2014 ( 11 )   2014.11

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    We propose a simple,. but effective mechanism to realize an inflationary earl universe consistent with the observed WMAP, Planck and/or BICEP2 data, which would be incorporated in various supersymmetric models of elementary particles constructed in the (effective) five-dimensional spacetime. In our scenario, the inflaton field is identified with one of the moduli appearing when the fifth direction is compactified, and a successful cosmological inflation without the so-called eta problem can be achieved by a very simple moduli stabilization potential. We also discuss the related particle cosmology during and (just) after the inflation, such as the (no) cosmological moduli problem.

    DOI: 10.1088/1475-7516/2014/11/027

  • The higgs boson mass in a natural minimal supersymmetric standard model with nonuniversal gaugino masses at the grand unification theory scale Reviewed

    Hiroyuki Abe, Junichiro Kawamura, Hajime Otsuka

    Progress of Theoretical and Experimental Physics   2013 ( 1 )   2013.1

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    We identify a parameter region where the mass of the lightest CP-even Higgs boson resides at 124.4-126.8 GeV, and at the same time the degree of tuning a Higgsino-mass parameter (the so-called mu-parameter) is relaxed above 10% in the minimal supersymmetric standard model (MSSM) with soft supersymmetry breaking terms, by solving the full set of one-loop renormalization group equations numerically. It is found that certain nonuniversal values of gaugino-mass parameters at the so-called grand unification theory (GUT) scale similar to 10(16) GeV are important ingredients for the MSSM to predict, without severe fine-tuning, the Higgs boson mass similar to 125 GeV, indicated by recent observations at the Large Hadron Collider. We also show a typical superparticle spectrum in this parameter region.

    DOI: 10.1093/ptep/pts041

  • SUSY flavor structure of generic 5D supergravity models Reviewed

    Hiroyuki Abe, Hajime Otsuka, Yutaka Sakamura, Yusuke Yamada

    European Physical Journal C   72 ( 5 )   1 - 22   2012.5

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    We perform a comprehensive and systematic analysis of the SUSY flavor structure of generic 5D supergravity models on S-1/Z(2) with multiple Z(2)-odd vector multiplets that generate multiple moduli. The SUSY flavor problem can be avoided due to contact terms in the 4D effective Kahler potential peculiar to the multi-moduli case. A detailed phenomenological analysis is provided based on an illustrative model.

    DOI: 10.1140/epjc/s10052-012-2018-x

▼display all

Presentations

  • Yukawa textures from non-invertible symmetries

    大塚啓

    第130回日本物理学会九州支部例会  2024.11 

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    Event date: 2024.11

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Machine learning-based stastical search strategy for particle and string phenomenology

    Hajime Otsuka

    R6 年度学術変革 A「学習物理」領域会議  2024.9 

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    Event date: 2024.9

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Stringy constraints on primordial electromagnetic fields in axion inflation

    Hajime Otsuka

    日本物理学会第79回年次大会  2024.9 

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    Event date: 2024.9

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Non-invertible flavor symmetries in magnetized extra dimensions Invited

    Hajime Otsuka

    これまでとこれからの、 素粒子と弦の現象論  2024.9 

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    Event date: 2024.9

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

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  • Non-invertible flavor symmetries in magnetized extra dimensions

    Hajime Otsuka

    Particle Physics and Cosmology from String Compactification" 3rd meeting  2024.9 

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    Event date: 2024.9

    Language:English   Presentation type:Oral presentation (general)  

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  • Non-invertible flavor symmetries in magnetized extra dimensions

    大塚啓

    素粒子物理学の進展2024(PPP2024)  2024.8 

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    Event date: 2024.8

    Language:Japanese  

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  • Non-invertible flavor symmetries in magnetized extra dimensions

    大塚啓

    場の理論と弦理論 2024  2024.8 

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  • Stringy constraints on primordial electromagnetic fields in axion inflation Invited

    大塚啓

    量子重力の視点で探る 宇宙のダークサイド  2024.8 

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    Event date: 2024.8

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Stringy constraints on primordial electromagnetic fields in axion inflation Invited

    Hajime Otsuka

    Seminar at Osaka University  2024.5 

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    Event date: 2024.5

    Language:English   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

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  • Top-down modular invariance approach to flavour II Invited

    Hajime Otsuka

    Modular Invariance Approach to the Lepton and Quark Flavour Problems: from Bottom-up to Top-down  2024.5 

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  • Modular Flavor Symmetry in Heterotic &#36;E_6&#36; GUT Invited

    Hajime Otsuka

    Workshop on Grand Unified Theory, Phenomenology and Cosmology (GUTPC)  2024.4 

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    Event date: 2024.4

    Language:English  

    Country:Other  

    Modular Flavor Symmetry in Heterotic &#36;E_6&#36; GUT

  • Modular Flavor Symmetry in Heterotic $E_6$ GUT Invited

    Hajime Otsuka

    Workshop on Grand Unified Theory, Phenomenology and Cosmology (GUTPC)  2024.4 

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    Event date: 2024.4

    Language:English   Presentation type:Oral presentation (invited, special)  

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  • Sequestered String Models imply Split Supersymmetry

    大塚啓

    日本物理学会2024年春季大会  2024.3 

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    Event date: 2024.3

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    Sequestered String Models imply Split Supersymmetry

  • Sequestered String Models imply Split Supersymmetry

    Hajime Otsuka

    日本物理学会2024年春季大会  2024.3 

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    Event date: 2024.3

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Modular forms and hierarchical Yukawa couplings in heterotic Calabi-Yau compactifications

    Hajime Otsuka

    "Particle Physics and Cosmology from String Compactification" 2nd meeting  2024.2 

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    Event date: 2024.2

    Language:Japanese  

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    Modular forms and hierarchical Yukawa couplings in heterotic Calabi-Yau compactifications

  • Modular forms and hierarchical Yukawa couplings in heterotic Calabi-Yau compactifications

    Hajime Otsuka

    "Particle Physics and Cosmology from String Compactification" 2nd meeting  2024.2 

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    Event date: 2024.2

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Sequestered String Models imply Split Supersymmetry

    大塚啓

    第129回日本物理学会九州支部例会  2023.12 

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    Event date: 2023.12

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    Sequestered String Models imply Split Supersymmetry

  • Sequestered String Models imply Split Supersymmetry

    Hajime Otsuka

    第129回日本物理学会九州支部例会  2023.12 

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    Event date: 2023.12

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Sequestered String Models imply Split Supersymmetry

    Hajime Otsuka

    KEK Theory Workshop 2023  2023.11 

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    Event date: 2023.11 - 2023.12

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    Country:Other  

    Sequestered String Models imply Split Supersymmetry

  • Sequestered String Models imply Split Supersymmetry

    Hajime Otsuka

    KEK Theory Workshop 2023  2023.11 

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    Event date: 2023.11 - 2023.12

    Language:English   Presentation type:Oral presentation (general)  

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  • Flavor, CP and Modular Symmetries from the top down and the bottom up Invited

    Hajime Otsuka

    KEK Theory Meeting on Particle Physics Phenomenology (KEK-PH2023)  2023.11 

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    Event date: 2023.11

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    Country:Other  

    Flavor, CP and Modular Symmetries from the top down and the bottom up

  • Flavor, CP and Modular Symmetries from the top down and the bottom up Invited

    Hajime Otsuka

    KEK Theory Meeting on Particle Physics Phenomenology (KEK-PH2023)  2023.11 

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    Event date: 2023.11

    Language:English   Presentation type:Oral presentation (invited, special)  

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  • Upper bound on the Atiyah–Singer index from tadpole cancellation

    Hajime Otsuka

    日本物理学会第78回年次大会  2023.9 

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    Event date: 2023.9

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    Upper bound on the Atiyah–Singer index from tadpole cancellation

  • Upper bound on the Atiyah–Singer index from tadpole cancellation

    Hajime Otsuka

    日本物理学会第78回年次大会  2023.9 

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    Event date: 2023.9

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Open challenges for string phenomenology

    Hajime Otsuka

    Particle Physics and Cosmology from String Compactification  2023.9 

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    Event date: 2023.9

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    Open challenges for string phenomenology

  • Open challenges for string phenomenology

    Hajime Otsuka

    Particle Physics and Cosmology from String Compactification  2023.9 

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    Event date: 2023.9

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Upper bound on the Atiyah–Singer index from tadpole cancellation

    Hajime Otsuka

    場の理論と弦理論 2023  2023.8 

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    Event date: 2023.8

    Language:Japanese  

    Country:Other  

    Upper bound on the Atiyah–Singer index from tadpole cancellation

  • Upper bound on the Atiyah–Singer index from tadpole cancellation

    Hajime Otsuka

    場の理論と弦理論 2023  2023.8 

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    Event date: 2023.8

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Upper bound on the Atiyah–Singer index from tadpole cancellation

    Hajime Otsuka

    String phenomenology 2023  2023.7 

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    Event date: 2023.7

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    Country:Other  

    Upper bound on the Atiyah–Singer index from tadpole cancellation

  • Upper bound on the Atiyah–Singer index from tadpole cancellation

    Hajime Otsuka

    String phenomenology 2023  2023.7 

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    Event date: 2023.7

    Language:English   Presentation type:Oral presentation (general)  

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  • Discrete symmetries in Type IIB MSSM flux vacua

    Hajime Otsuka

    日本物理学会2023年春季大会  2023.3 

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    Event date: 2023.3

    Language:Japanese  

    Country:Other  

    Discrete symmetries in Type IIB MSSM flux vacua

  • Discrete symmetries in Type IIB MSSM flux vacua

    Hajime Otsuka

    日本物理学会2023年春季大会  2023.3 

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    Event date: 2023.3

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Modular flavor symmetries and CP from string theory Invited

    Hajime Otsuka

    Seminar at Theoretical Particle and Hadron Physics Group, Hiroshima University  2023.3 

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    Event date: 2023.3

    Language:English  

    Country:Other  

    Modular flavor symmetries and CP from string theory

  • Modular flavor symmetries and CP from string theory Invited

    Hajime Otsuka

    Seminar at Theoretical Particle and Hadron Physics Group, Hiroshima University  2023.3 

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    Event date: 2023.3

    Language:English   Presentation type:Oral presentation (general)  

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  • Modular symmetry in the string EFT Invited

    Hajime Otsuka

    Kagoshima Workshop on Particles, Fields and Strings 2023  2023.2 

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    Event date: 2023.2

    Language:Japanese  

    Country:Other  

    Modular symmetry in the string EFT

  • Modular symmetry in the string EFT Invited

    Hajime Otsuka

    Kagoshima Workshop on Particles, Fields and Strings 2023  2023.2 

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    Event date: 2023.2

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Hierarchical structure of physical Yukawa couplings from matter field Kähler metric

    Hajime Otsuka

    KEK Theory Workshop 2022  2022.12 

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    Event date: 2022.12

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    Country:Other  

    Hierarchical structure of physical Yukawa couplings from matter field Kähler metric

  • Hierarchical structure of physical Yukawa couplings from matter field Kähler metric

    Hajime Otsuka

    KEK Theory Workshop 2022  2022.12 

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    Event date: 2022.12

    Language:English   Presentation type:Oral presentation (general)  

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  • Modular symmetry in the SMEFT

    Hajime Otsuka

    KEK Theory Meeting on Particle Physics Phenomenology (KEK-PH2022)  2022.11 

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    Event date: 2022.11 - 2022.12

    Language:English  

    Country:Other  

    Modular symmetry in the SMEFT

  • Modular symmetry in the SMEFT

    Hajime Otsuka

    KEK Theory Meeting on Particle Physics Phenomenology (KEK-PH2022)  2022.11 

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    Event date: 2022.11 - 2022.12

    Language:English   Presentation type:Oral presentation (general)  

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  • Generalized Matter Parities from Finite Modular Symmetries

    Hajime Otsuka

    Summer Institute 2022  2022.9 

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    Event date: 2022.9

    Language:English  

    Country:Other  

    Generalized Matter Parities from Finite Modular Symmetries

  • Generalized Matter Parities from Finite Modular Symmetries

    Hajime Otsuka

    Summer Institute 2022  2022.9 

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    Event date: 2022.9

    Language:English   Presentation type:Poster presentation  

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  • モジュラー対称性に基づくフレーバー模型のランドスケープによる補正

    石黒奎弥, 大塚啓, 岡田寛

    日本物理学会2022年秋季大会  2022.9 

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    Event date: 2022.9

    Language:Japanese  

    Country:Other  

  • 弦理論から迫るフレーバーとCPの物理 Invited

    大塚啓

    日本物理学会2022年秋季大会  2022.9 

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    Event date: 2022.9

    Language:Japanese  

    Country:Other  

  • モジュラー対称性に基づくフレーバー模型のランドスケープによる補正

    石黒奎弥, 大塚啓, 岡田寛

    日本物理学会2022年秋季大会  2022.9 

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    Event date: 2022.9

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 弦理論から迫るフレーバーとCPの物理 Invited

    大塚啓

    日本物理学会2022年秋季大会  2022.9 

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    Event date: 2022.9

    Language:Japanese   Presentation type:Symposium, workshop panel (public)  

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  • Sharpening the Boundaries Between Flux Landscape and Swampland by Tadpole Charge

    Hajime Otsuka

    場の理論と弦理論 2022  2022.8 

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    Event date: 2022.8

    Language:Japanese  

    Country:Other  

    Sharpening the Boundaries Between Flux Landscape and Swampland by Tadpole Charge

  • Sharpening the Boundaries Between Flux Landscape and Swampland by Tadpole Charge

    Hajime Otsuka

    場の理論と弦理論 2022  2022.8 

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    Event date: 2022.8

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Modular flavor symmetry in the string EFT Invited

    Hajime Otsuka

    Bethe Forum on Modular Flavor Symmetries  2022.5 

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    Event date: 2022.5

    Language:English  

    Country:Other  

    Modular flavor symmetry in the string EFT

  • Modular flavor symmetry in the string EFT Invited

    Hajime Otsuka

    Bethe Forum on Modular Flavor Symmetries  2022.5 

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    Event date: 2022.5

    Language:English   Presentation type:Oral presentation (invited, special)  

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  • Hidden structures in the landscape of heterotic line bundle models Invited International conference

    大塚啓

    KEK Theory Workshop 2020  2021.12 

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    Event date: 2021.12

    Language:English  

    Venue:KEK (online)   Country:Other  

    Hidden structures in the landscape of heterotic line bundle models

  • Small flux superpotential in F-theory compactifications International conference

    大塚啓

    KEK Theory Workshop 2021  2021.12 

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    Event date: 2021.12

    Language:English  

    Venue:KEK(Online)   Country:Japan  

    Small flux superpotential in F-theory compactifications

  • Small flux superpotential in F-theory compactifications Invited International conference

    大塚啓

    Dark World to Swampland 2021  2021.11 

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    Event date: 2021.11

    Language:English  

    Venue:Online   Country:Korea, Republic of  

    Small flux superpotential in F-theory compactifications

  • Stringy Origin of Minimal Flavor Violation Invited International conference

    大塚啓

    Recent development of flavor symmetry  2021.11 

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    Event date: 2021.11

    Language:English  

    Venue:APCTP(Online)   Country:Korea, Republic of  

    Stringy Origin of Minimal Flavor Violation

  • Stringy Origin of Minimal Flavor Violation

    大塚啓

    日本物理学会2021年秋季大会  2021.9 

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    Event date: 2021.9

    Language:Japanese  

    Venue:Online   Country:Japan  

    Stringy Origin of Minimal Flavor Violation

  • Stringy origin of modular flavor symmetry and spontaneous CP violation

    大塚啓

    SUSY 2021  2021.8 

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    Event date: 2021.8

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    Stringy origin of modular flavor symmetry and spontaneous CP violation

  • Hidden structures in the landscape of heterotic line bundle models

    大塚啓

    Strings and Fields 2021  2021.8 

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    Event date: 2021.8

    Language:English  

    Venue:京都大学(Online)   Country:Japan  

    Hidden structures in the landscape of heterotic line bundle models

  • Symplectic modular symmetry in heterotic string vacua: flavor, CP, and R-symmetries

    大塚啓

    Asia-Pacific Workshop on Particle Physics and Cosmology 2021  2021.8 

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    Event date: 2021.8

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    Symplectic modular symmetry in heterotic string vacua: flavor, CP, and R-symmetries

  • Spontaneous CP violation and symplectic modular symmetry in Calabi-Yau compactifications

    大塚啓

    日本物理学会第76回年次大会  2021.3 

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    Event date: 2021.3

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    Spontaneous CP violation and symplectic modular symmetry in Calabi-Yau compactifications

  • Spontaneous CP violation and symplectic modular symmetry in Calabi-Yau compactifications

    大塚啓

    Strings and Fields 2020  2020.11 

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    Event date: 2020.11

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    Spontaneous CP violation and symplectic modular symmetry in Calabi-Yau compactifications

  • Deep learning and k-means clustering in heterotic string vacua with line bundles

    大塚啓

    日本物理学会2020年秋季大会  2020.9 

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    Event date: 2020.9

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    Deep learning and k-means clustering in heterotic string vacua with line bundles

  • Modular symmetry in Type IIB flux vacua

    大塚啓

    KEK Theory Meeting on Particle Physics Phenomenology 2020  2020.2 

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    Event date: 2020.2

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    Modular symmetry in Type IIB flux vacua

  • Magnetized Blow-up models Invited

    大塚啓

    Branes, supergravity and string phenomenology  2020.2 

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    Event date: 2020.2

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    Magnetized Blow-up models

  • Wavefunctions and Yukawa couplings on resolutions of C^n/Z_n orbifolds

    大塚啓

    KEK Theory Workshop 2019  2019.12 

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    Event date: 2019.12

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    Wavefunctions and Yukawa couplings on resolutions of C^n/Z_n orbifolds

  • Zero-mode Wavefunctions on Resolutions of C^n/Z_n Orbifolds

    大塚啓

    日本物理学会2019年秋季大会  2019.9 

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    Event date: 2019.9

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    Zero-mode Wavefunctions on Resolutions of C^n/Z_n Orbifolds

  • Landscape of four-dimensional F-theory flux vacua

    大塚啓

    Strings and Fields 2019  2019.8 

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    Event date: 2019.8

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    Landscape of four-dimensional F-theory flux vacua

  • Cosmological constant at finite string coupling in F-theory flux compactifications

    大塚啓

    String Phenomenology 2019  2019.6 

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    Event date: 2019.6

    Language:English  

    Country:Other  

    Cosmological constant at finite string coupling in F-theory flux compactifications

  • Cosmological constant at finite string coupling in F-theory flux compactifications Invited

    大塚啓

    The third NRF-JSPS workshop in particle physics, cosmology, and gravitation  2019.6 

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    Event date: 2019.6

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    Cosmological constant at finite string coupling in F-theory flux compactifications

  • On the vacuum structure of F-theory compactifications Invited

    大塚啓

    KEK Theory Workshop 2018 Dec.  2018.12 

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    Event date: 2018.12

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    On the vacuum structure of F-theory compactifications

  • Hypercharge flux in SO(32) heterotic string theory

    大塚啓

    基研研究会 素粒子物理学の進展2018  2018.8 

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    Event date: 2018.8

    Language:Japanese  

    Venue:京都大学基礎物理学研究所   Country:Japan  

    Hypercharge flux in SO(32) heterotic string theory

  • Hypercharge flux in SO(32) heterotic string theory

    大塚啓

    Strings and Fields 2018  2018.8 

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    Event date: 2018.7 - 2018.8

    Language:English  

    Country:Other  

    Hypercharge flux in SO(32) heterotic string theory

  • SO(32) Heterotic Line Bundle Models

    大塚啓

    String Phenomenology 2018  2018.7 

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    Event date: 2018.7

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    SO(32) Heterotic Line Bundle Models

  • Radiative Kaehler moduli stabilization

    大塚啓

    日本物理学会第73回年次大会  2018.3 

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    Event date: 2018.3

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    Radiative Kaehler moduli stabilization

  • Axion decay constants at special points in type II string theory Invited

    大塚啓

    Mini-workshop on inflation, mirror symmetry and F-theory  2018.3 

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    Event date: 2018.3

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    Axion decay constants at special points in type II string theory

  • Heterotic Stringy Corrections to Metrics of Toroidal Orbifolds and Their Resolutions

    大塚啓

    日本物理学会第74回年次大会  2018.3 

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    Event date: 2018.3

    Language:Japanese  

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    Heterotic Stringy Corrections to Metrics of Toroidal Orbifolds and Their Resolutions

  • Radiative Kaehler moduli stabilization Invited

    大塚啓

    Focus Meeting: new perspectives on light particles  2017.11 

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    Event date: 2017.11 - 2017.12

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    Radiative Kaehler moduli stabilization

  • SO(32) heterotic line bundle models

    大塚啓

    日本物理学会 2017年秋季大会  2017.9 

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    Event date: 2017.9

    Language:Japanese  

    Country:Other  

    SO(32) heterotic line bundle models

  • Three-generation models in SO(32) heterotic string theory

    大塚啓

    Summer Institute 2017  2017.8 

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    Event date: 2017.8

    Language:English  

    Country:Other  

    Three-generation models in SO(32) heterotic string theory

  • SO(32) heterotic line bundle models

    大塚啓

    Strings and Fields 2017  2017.8 

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    Event date: 2017.8

    Language:English  

    Country:Other  

    SO(32) heterotic line bundle models

  • On the Flux Vacua in F-theory Compactifications

    大塚啓

    Exceptional Groups as Symmetries of Nature’17  2017.7 

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    Event date: 2017.7

    Language:Japanese  

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    On the Flux Vacua in F-theory Compactifications

  • On the Vacuum Structure of F-theory Compactifications

    大塚啓

    String Phenomenology 2017  2017.7 

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    Event date: 2017.7

    Language:English  

    Country:Other  

    On the Vacuum Structure of F-theory Compactifications

  • On the vacuum structure of F-theory compactifications

    大塚啓

    PASCOS 2017  2017.6 

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    Event date: 2017.6

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    On the vacuum structure of F-theory compactifications

  • Affleck-Dine baryogenesis on an axion background

    大塚啓

    The 5th UTQuest Workshop, “Hidden Sector Physics and Cosmophysics”  2016.12 

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    Event date: 2016.12

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    Affleck-Dine baryogenesis on an axion background

  • Affleck-Dine baryogenesis on an axion background Invited

    大塚啓

    Focus Workshop on Particle Physics and Cosmology  2016.12 

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    Event date: 2016.12

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    Affleck-Dine baryogenesis on an axion background

  • Axion decay constants at special points in type II superstring theory Invited

    大塚啓

    HU-IBS Sapporo Summer Institute on Particle Physics and Cosmology  2016.8 

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    Event date: 2016.8

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    Country:Other  

    Axion decay constants at special points in type II superstring theory

  • Axion decay constants at special points in type II superstring theory

    大塚啓

    Strings and Fields 2016  2016.8 

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    Event date: 2016.8

    Language:English  

    Country:Other  

    Axion decay constants at special points in type II superstring theory

  • Three-generation models from SO(32) heterotic string theory

    大塚啓

    Pascos 2016  2016.7 

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    Event date: 2016.7

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    Three-generation models from SO(32) heterotic string theory

  • New forms of potential for string axion inflation

    大塚啓

    KEK Theory Workshop 2015 Dec.  2015.12 

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    Event date: 2015.12

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    Country:Other  

    New forms of potential for string axion inflation

  • Three-generation models in SO(32) heterotic string theory

    大塚啓

    基研研究会 素粒子物理学の進展2015  2015.9 

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    Event date: 2015.9

    Language:Japanese  

    Country:Other  

    Three-generation models in SO(32) heterotic string theory

  • Natural inflation with and without modulations in string theory

    大塚啓

    String Phenomenology 2015  2015.6 

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    Event date: 2015.6

    Language:English  

    Country:Other  

    Natural inflation with and without modulations in string theory

  • Natural inflation with and without modulations in type IIB string theory

    大塚啓

    日本物理学会第70年年次大会  2015.3 

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    Event date: 2015.3

    Language:Japanese  

    Country:Other  

    Natural inflation with and without modulations in type IIB string theory

  • Natural inflation with and without modulations in string theory

    大塚啓

    KEK theory workshop 2015  2015.1 

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    Event date: 2015.1

    Language:English  

    Country:Other  

    Natural inflation with and without modulations in string theory

  • Towards natural inflation from the weakly coupled heterotic string theory

    大塚啓

    Workshop on geometry, extra dimensions and string phenomenology in Miyazaki  2014.11 

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    Event date: 2014.11

    Language:Japanese  

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    Towards natural inflation from the weakly coupled heterotic string theory

  • Towards natural inflation from the weakly coupled heterotic string theory with magnetic fluxes

    大塚啓

    日本物理学会2014年秋季大会  2014.9 

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    Event date: 2014.9

    Language:Japanese  

    Country:Other  

    Towards natural inflation from the weakly coupled heterotic string theory with magnetic fluxes

  • Moduli inflation in 5D SUGRA

    大塚啓

    SUSY 2014  2014.7 

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    Event date: 2014.7

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    Country:Other  

    Moduli inflation in 5D SUGRA

  • The Higgs boson mass in a natural MSSM with nonuniversal gaugino masses

    大塚啓

    PASCOS 2013  2013.11 

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    Event date: 2013.11

    Language:English  

    Country:Other  

    The Higgs boson mass in a natural MSSM with nonuniversal gaugino masses

  • Moduli inflation and gravitino dark matter

    大塚啓

    日本物理学会第68回年次大会  2013.3 

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    Event date: 2013.3

    Language:Japanese  

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    Moduli inflation and gravitino dark matter

  • Moduli inflation and gravitino dark matter in 5D SUGRA

    大塚啓

    KEK Theory Meeting on Particle Physics Phenomenology 2013  2013.3 

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    Event date: 2013.3

    Language:English  

    Country:Other  

    Moduli inflation and gravitino dark matter in 5D SUGRA

  • The Higgs boson mass in a natural MSSM with nonuniversal gaugino masses at the GUT scale

    大塚啓

    Higgs Coupling 2012  2012.11 

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    Event date: 2012.11

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    The Higgs boson mass in a natural MSSM with nonuniversal gaugino masses at the GUT scale

  • Gravitino dark matter in the gravity-mediated supersymmetry breaking

    大塚啓

    日本物理学会2012年秋季大会  2012.9 

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    Event date: 2012.9

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    Gravitino dark matter in the gravity-mediated supersymmetry breaking

  • Phenomenology 5D SUGRA models with multi moduli

    大塚啓

    日本物理学会第67回年次大会  2012.3 

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    Event date: 2012.3

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    Phenomenology 5D SUGRA models with multi moduli

  • 機械学習を用いた 弦理論の真空構造解明

    Hajime Otsuka

    数理・データサイエンスに関する教育・研究支援プログラム 研究成果発表会  2023.1 

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    機械学習を用いた 弦理論の真空構造解明

  • Hierarchical structure of physical Yukawa couplings from matter field Kähler metric Invited

    Hajime Otsuka

    Recent development of Modular Flavor Symmetry  2023.3 

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    Hierarchical structure of physical Yukawa couplings from matter field Kähler metric

  • 機械学習を用いた 弦理論の真空構造解明

    Hajime Otsuka

    数理・データサイエンスに関する教育・研究支援プログラム 研究成果発表会  2023.1 

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    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Hierarchical structure of physical Yukawa couplings from matter field Kähler metric Invited

    Hajime Otsuka

    Recent development of Modular Flavor Symmetry  2023.3 

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MISC

  • 特集・時空概念と物理学の発展「超弦時空と機械学習」

    大塚啓

    数理科学   2020.12

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  • Pseudo-Nambu-Goldstone Dark Matter from Non-Abelian Gauge Symmetry

    大塚啓, 下村崇, 下村崇, 津村浩二, 内田祥紀, 山津直樹

    日本物理学会講演概要集(CD-ROM)   78 ( 1 )   2023   ISSN:2189-079X

Professional Memberships

  • 日本物理学会

Academic Activities

  • 世話人

    "Particle Physics and Cosmology from String Compactification" 2nd meeting  ( Japan ) 2024.2

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    Type:Competition, symposium, etc. 

  • 座長

    第128回日本物理学会九州支部例会  ( Japan ) 2023.12

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    Type:Competition, symposium, etc. 

  • 世話人

    Particle Physics and Cosmology from String Compactification  ( Japan ) 2023.9

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    Type:Competition, symposium, etc. 

  • 世話人

    Kagoshima Workshop on Particles, Fields and Strings 2023  ( Sunplaza Tenmonkan, Kagoshima Japan ) 2023.2

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    Type:Competition, symposium, etc. 

  • 世話人 International contribution

    KEK Theory workshop 2021  ( Online Japan ) 2021.12

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    Type:Competition, symposium, etc. 

  • 座長

    日本物理学会2021年秋季大会  ( Japan ) 2021.9

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    Type:Competition, symposium, etc. 

  • 世話人 International contribution

    KEK Theory workshop 2020  ( Online Japan ) 2020.12

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    Type:Competition, symposium, etc. 

  • 座長

    日本物理学会2020年秋季大会  ( Japan ) 2020.9

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    Type:Competition, symposium, etc. 

  • 世話人 International contribution

    KEK Theory Meeting on Particle Physics Phenomenology (KEK-PH2020)  ( Japan ) 2020.2

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    Type:Competition, symposium, etc. 

  • 世話人 International contribution

    KEK Theory workshop 2019  ( Japan ) 2019.12

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Research Projects

  • 機械学習を用いた弦の有効理論の構築

    Grant number:23H04512  2023 - 2024

    Japan Society for the Promotion of Science・Ministry of Education, Culture, Sports, Science and Technology  Grants-in-Aid for Scientific Research  Grant-in-Aid for Transformative Research Areas (A)

    大塚 啓

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    Authorship:Principal investigator  Grant type:Scientific research funding

    理論的・実験的問題点が指摘されている素粒子標準模型の拡張に当たり、ゲージ及び重力相互作用を統一的に記述し素粒子統一理論の候補と期待される超弦理論に注目する。余剰次元空間を予言する弦理論において、真空解であるカラビヤウ多様体は無数に存在し、その有効理論の構造は解明されていない。本研究では、機械学習/深層学習を用いて、カラビヤウ多様体上の超弦理論の有効理論の全貌を明らかにすることを目的とする。

    CiNii Research

  • 機械学習を用いた弦理論の真空構造解明

    2022

    「数理・データサイエンスに関する教育・研究支援プログラム」 (九州大学数理・データサイエンス教育研究センター)

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    Authorship:Principal investigator  Grant type:On-campus funds, funds, etc.

  • オービフォールド特異点の解消とその現象論的応用

    Grant number:20K14477  2020 - 2023

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Early-Career Scientists

    大塚 啓

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    Authorship:Principal investigator  Grant type:Scientific research funding

    理論的・実験的問題点が指摘されている素粒子物理学における標準模型(素粒子標準模型) の拡張に当たり、ゲージ及び重力相互作用を統一的に記述する超弦理論は素粒子統一理論の有力な候補である。本研究は、オービフォールド特異点の解消された余剰次元空間上の超弦理論の有効理論に注目する。特異点解消に付随して現れるブローアップモードの物理を介して超弦理論の痕跡を探ることを目的とする。

    CiNii Research

  • 滑らかなカラビ・ヤウ多様体上のヘテロ型弦理論における素粒子現象論

    Grant number:19J00664  2019 - 2021

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for JSPS Fellows

    大塚 啓

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    Authorship:Principal investigator  Grant type:Scientific research funding

    素粒子標準模型では、素粒子の質量及びフレーバー構造を決定する湯川結合はパラメターであり、それらの値を予言することはできない。本研究の目的は、湯川結合の起源を弦理論、特に滑らかなカラビ・ヤウ多様体上のヘテロ型弦理論に基づいて明らかにすることである。曲率を持つ滑らかなカラビ・ヤウ多様体上のSO(32)ヘテロ型弦理論に基づく有効理論に注目し、実験データと整合する湯川結合の導出を目指す。また、モジュライ場及びアクシオン場に依存する湯川結合を通して、これらモジュライ場の引き起こす素粒子論的・宇宙論的現象を探求する。

    CiNii Research

  • CP対称性の破れを担うアクシオン場の現象論的研究

    Grant number:17K14303  2017 - 2018

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Young Scientists(A)or(B)

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    Authorship:Principal investigator  Grant type:Scientific research funding

  • 超弦理論を背景とする5次元超重力理論の素粒子現象論及び宇宙論

    Grant number:14J07296  2014 - 2015

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for JSPS Fellows

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    Authorship:Principal investigator  Grant type:Scientific research funding

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Educational Activities

  • 学部専門教育として、電磁気学Ⅰ・同演習、物理数学演習Ⅰ、物理数学演習Ⅱ、物理学ゼミナール、M1ゼミナールを担当。
    大学院生への研究指導。

Class subject

  • 物理数学演習Ⅱ

    2024.12 - 2025.2   Winter quarter

  • 物理数学演習(R2以前入学者用)

    2024.10 - 2025.3   Second semester

  • 物理数学演習Ⅰ

    2024.10 - 2024.12   Fall quarter

  • 電磁気学Ⅰ・同演習

    2024.4 - 2024.9   First semester

  • 物理数学演習Ⅱ

    2023.12 - 2024.2   Winter quarter

  • 物理数学演習(R2以前入学者用)

    2023.10 - 2024.3   Second semester

  • 物理数学演習Ⅰ

    2023.10 - 2023.12   Fall quarter

  • 電磁気学Ⅰ・同演習

    2023.4 - 2023.9   First semester

  • 物理数学演習Ⅱ

    2022.12 - 2023.2   Winter quarter

  • 物理学ゼミナール

    2022.10 - 2023.3   Second semester

  • 物理数学演習Ⅰ

    2022.10 - 2022.12   Fall quarter

  • 電磁気学Ⅰ・同演習

    2022.4 - 2022.9   First semester

  • 物理数学演習Ⅱ

    2024.12 - 2025.2   Winter quarter

  • 物理数学演習(R2以前入学者用)

    2024.10 - 2025.3   Second semester

  • 物理数学演習Ⅰ

    2024.10 - 2024.12   Fall quarter

  • 電磁気学Ⅰ・同演習

    2024.4 - 2024.9   First semester

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FD Participation

  • 2023.3   Role:Speech   Title:【物理学科FD】物理数学の教育と効果的な演習に向けて

    Organizer:Undergraduate school department

  • 2022.4   Role:Participation   Title:令和4年度 第1回全学FD(新任教員の研修)The 1st All-University FD (training for new faculty members) in FY2022

    Organizer:University-wide

  • 2022.3   Role:Participation   Title:【物理学科FD】ティーチング・フェロー制度の概要と講義での活用に向けて

    Organizer:Undergraduate school department

Visiting, concurrent, or part-time lecturers at other universities, institutions, etc.

  • 2023  北海道大学  Classification:Intensive course  Domestic/International Classification:Japan 

Other educational activity and Special note

  • 2024  Class Teacher  学部

  • 2023  Class Teacher  学部

Social Activities

  • 高校1・2年生を対象にした体験講義

    九州大学理学部物理学科 第26回体験物理学  九州大学  2023.3

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    Audience:General, Scientific, Company, Civic organization, Governmental agency

    Type:Lecture

Travel Abroad

  • 2024.5

    Staying countory name 1:Germany   Staying institution name 1:Mainz Institute for Theoretical Physics

  • 2024.4

    Staying countory name 1:China   Staying institution name 1:Hangzhou Institute for Advanced Study (HIAS), University of Chinese Academy of Sciences (UCAS)

  • 2023.6

    Staying countory name 1:Korea, Republic of   Staying institution name 1:IBS

  • 2022.10 - 2022.11

    Staying countory name 1:Korea, Republic of   Staying institution name 1:APCTP

  • 2022.5

    Staying countory name 1:Germany   Staying institution name 1:Bethe Center for Theoretical Physics

  • 2022.4

    Staying countory name 1:Italy   Staying institution name 1:Bologna University

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