Details of the Researcher

PHOTO

Masaki Yamada
Section
Graduate School of Science
Job title
Associate Professor
Degree

  • 博士（理学）（東京大学）

  • 修士（理学）（東京大学）

Researcher ID
ABD-6496-2020

Research History 8

  • 2025/01 - Present
    Tohoku University　Graduate School of Science　Associate Professor

  • 2020/01 - 2024/12
    Tohoku University　FRIS　Assistant professor

  • 2019/09 - 2020/04
    MIT

  • 2017/09 - 2019/08
    Tufts University

  • 2016/09 - 2017/08
    Tufts University

  • 2016/04 - 2017/08
    Tohoku University

  • 2013/04 - 2016/03
    ICRR, The University of Tokyo

  • 2012/12 - 2016/03
    The University of Tokyo　Institute for Cosmic Ray Research　Program for the Leading Graduate Course for Frontiers of Mathematical Sciences and Physics

Show all Show first 5

Education 3

  • The University of Tokyo　Department of Physics

    2013/04 - 2016/03

  • The University of Tokyo

    2011/04 - 2013/03

  • 東京大学　理科一類 (理学部物理学科)

    2007/04 - 2011/03

Professional Memberships 3

  • 理論天文学宇宙物理学懇談会

    2014/12 - Present

  • 日本物理学会

    2012/12 - Present

  • 素粒子論グループ

    2011/04 - Present

Research Interests 5

  • Black hole

  • Baryon asymmetry

  • Dark matter

  • Inflation

  • Particle Cosmology

Research Areas 1

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

Awards 5

  1. 泉萩会奨励賞

    2023/10　泉萩会　電荷を持つブラックホールの球対称なスカラーヘアー

  2. 第 17 回素粒子メダル奨励賞

    2022/06　素粒子論委員会

  3. Allan M. Cormack Postdoctoral Fellowship

    2018/09　Tufts University

  4. Oral presentation award in ICRR Master and Doctor Thesis Workshop

    2016/02　ICRR, the University of Tokyo

  5. Poster presentation award in ICRR Master and Doctor Thesis Workshop

    2015/02　ICRR, the University of Tokyo　Gravitational waves as a probe of supersymmetric scale

Papers 91

  1. Perturbative reheating and thermalization of pure Yang-Mills plasma Peer-reviewed

    Kyohei Mukaida, Masaki Yamada

    Journal of High Energy Physics　2024/05/15

    DOI： 10.1007/JHEP05(2024)174 　

  2. Dark baryon from pure Yang-Mills theory and its GW signature from cosmic strings Peer-reviewed

    Masaki Yamada, Kazuya Yonekura

    Journal of High Energy Physics　2023/09/28

    DOI： 10.1007/JHEP09(2023)197 　

  3. New Constraint on Primordial Lepton Flavor Asymmetries Peer-reviewed

    Valerie Domcke, Kohei Kamada, Kyohei Mukaida, Kai Schmitz, Masaki Yamada

    Physical Review Letters　2023/06/30

    DOI： 10.1103/PhysRevLett.130.261803 　

  4. Cosmic strings from pure Yang–Mills theory Peer-reviewed

    Masaki Yamada, Kazuya Yonekura

    Physical Review D　106　(12)　2022/12/21

    DOI： 10.1103/PhysRevD.106.123515 　

    ISSN： 2470-0010

    eISSN： 2470-0029

  5. Cascades of high-energy SM particles in the primordial thermal plasma Peer-reviewed

    Kyohei Mukaida, Masaki Yamada

    Journal of High Energy Physics　2022/10/18

    DOI： 10.1007/JHEP10(2022)116 　

  6. Baryon Asymmetry of the Universe from Lepton Flavor Violation Peer-reviewed

    Kyohei Mukaida, Kai Schmitz, Masaki Yamada

    Physical Review Letters　2022/06/28

    DOI： 10.1103/PhysRevLett.129.011803 　

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    Charged-lepton flavor violation (CLFV) is a smoking-gun signature of physics beyond the Standard Model. The discovery of CLFV in upcoming experiments would indicate that CLFV processes must have been efficient in the early Universe at relatively low temperatures. In this letter, we point out that such efficient CLFV interactions open up new ways of creating the baryon asymmetry of the Universe. First, we revisit the one-loop corrections from charged-lepton Yukawa interactions to the chemical transport in the Standard Model plasma, which imply that nonzero lepton flavor asymmetries summing up to $B-L = 0$ are enough to generate the baryon asymmetry. Then, we describe two scenarios of what we call {\it leptoflavorgenesis}, where efficient CLFV processes are responsible for the generation of primordial lepton flavor asymmetries that are subsequently converted to a baryon asymmetry by weak sphaleron processes. Here, the conversion factor from lepton flavor asymmetry to baryon asymmetry is suppressed by charged-lepton Yukawa couplings squared, which provides a natural explanation for the smallness of the observed baryon-to-photon ratio.

  7. Cosmic Birefringence Triggered by Dark Matter Domination Peer-reviewed

    Shota Nakagawa, Fuminobu Takahashi, Masaki Yamada

    Physical Review Letters　127　(18)　2021/10/28

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physrevlett.127.181103 　

    ISSN： 0031-9007 1079-7114

    eISSN： 1079-7114

  8. Wash-In Leptogenesis Peer-reviewed

    Valerie Domcke, Kohei Kamada, Kyohei Mukaida, Kai Schmitz, Masaki Yamada

    Physical Review Letters　126　(20)　2021/05/20

    Publisher: American Physical Society (APS)

    DOI： 10.1103/physrevlett.126.201802 　

    ISSN： 0031-9007

    eISSN： 1079-7114

  9. XENON1T Excess from Anomaly-Free Axionlike Dark Matter and Its Implications for Stellar Cooling Anomaly Peer-reviewed

    Fuminobu Takahashi, Masaki Yamada, Wen Yin

    Physical Review Letters　125　(16)　2020/10/12

    DOI： 10.1103/PhysRevLett.125.161801 　

    ISSN： 0031-9007

    eISSN： 1079-7114

  10. Spontaneous baryogenesis from axions with generic couplings Peer-reviewed

    Domcke, V., Ema, Y., Mukaida, K., Yamada, M.

    Journal of High Energy Physics　2020　(8)　2020

    DOI： 10.1007/JHEP08(2020)096 　

    ISSN： 2331-8422

  11. Spherically Symmetric Scalar Hair for Charged Black Holes Peer-reviewed

    Hong, J.-P., Suzuki, M., Yamada, M.

    Physical Review Letters　125　(11)　2020

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PHYSREVLETT.125.111104 　

  12. Primordial black holes from polynomial potentials in single field inflation Peer-reviewed

    Hertzberg, M.P., Yamada, M.

    Physical Review D　97　(8)　2018

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.97.083509 　

    ISSN： 2470-0010

  13. On longevity of I-ball/oscillon Peer-reviewed

    Mukaida, K., Takimoto, M., Yamada, M.

    Journal of High Energy Physics　2017　(3)　2017

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1007/JHEP03(2017)122 　

    ISSN： 1029-8479

  14. Inflation in random Gaussian landscapes Peer-reviewed

    Masoumi, A., Vilenkin, A., Yamada, M.

    Journal of Cosmology and Astroparticle Physics　2017　(5)　053-053　2017

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2017/05/053 　

    ISSN： 1475-7516

  15. Affleck-Dine baryogenesis just after inflation Peer-reviewed

    Yamada, M.

    Physical Review D　93　(8)　2016

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.93.083516 　

    ISSN： 2470-0010

  16. Cosmologically Safe QCD Axion without Fine-Tuning Peer-reviewed

    Yamada, M., Yanagida, T.T., Yonekura, K.

    Physical Review Letters　116　(5)　2016

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevLett.116.051801 　

    ISSN： 0031-9007

  17. Dark matter production in late time reheating Peer-reviewed

    Harigaya, K., Kawasaki, M., Mukaida, K., Yamada, M.

    Physical Review D - Particles, Fields, Gravitation and Cosmology　89　(8)　2014

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.89.083532 　

    ISSN： 1550-7998

  18. Thermalization and hotspot formation around small primordial black holes Peer-reviewed

    Minxi He, Kazunori Kohri, Kyohei Mukaida, Masaki Yamada

    Journal of Cosmology and Astroparticle Physics　2024　(10)　080-080　2024/10/01

    Publisher: IOP Publishing

    DOI： 10.1088/1475-7516/2024/10/080 　

    eISSN： 1475-7516

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    Abstract We quantitatively analyze a basic question: what is the stationary solution of the background plasma temperature profile around a black hole (BH)? One may naively expect that the temperature profile continuously decreases from the Hawking temperature at the surface of the BH towards an outer region. We show analytically and numerically that this is not the case because local thermal equilibrium cannot be maintained near the surface of the BH and also because the high-energy particles emitted from Hawking radiation cannot be instantaneously thermalized into the background plasma. The temperature profile has a plateau within a finite distance from the BH, and even the overall amplitude of background temperature at a distance far away from the BH is significantly suppressed compared with the naive expectation. The main reason for these counterintuitive results comes from the fact that the size of the BH is too small that particles of Hawking radiation goes far away within the typical time scale of interactions.

  19. Axion cogenesis without isocurvature perturbations Peer-reviewed

    Raymond T. Co, Masaki Yamada

    Physical Review D　2024/09/04

    DOI： 10.1103/PhysRevD.110.055009 　

  20. Thermal wash-in leptogenesis via heavy Higgs decay Peer-reviewed

    Kyohei Mukaida, Hidenaga Watanabe, Masaki Yamada

    Journal of Cosmology and Astroparticle Physics　2024/09/01

    DOI： 10.1088/1475-7516/2024/09/063 　

  21. Multifield stochastic dynamics in GUT hybrid inflation without monopole problem and with gravitational wave signatures of GUT Higgs representation Peer-reviewed

    Yuichiro Tada, Masaki Yamada

    Physics Letters B　2024/08

    DOI： 10.1016/j.physletb.2024.138854 　

  22. Super-slow phase transition catalyzed by BHs and the birth of baby BHs Peer-reviewed

    Ryusuke Jinno, Jun'ya Kume, Masaki Yamada

    Physics Letters B　2024/02

    DOI： 10.1016/j.physletb.2024.138465 　

  23. Dissipation of axion energy via the Schwinger and Witten effects Peer-reviewed

    Kwang Sik Jeong, Shota Nakagawa, Fuminobu Takahashi, Masaki Yamada

    Physical Review D　2024/01/16

    DOI： 10.1103/PhysRevD.109.015014 　

  24. Stochastic dynamics of multi-waterfall hybrid inflation and formation of primordial black holes Peer-reviewed

    Yuichiro Tada, Masaki Yamada

    Journal of Cosmology and Astroparticle Physics　2023/11/01

    DOI： 10.1088/1475-7516/2023/11/089 　

    ISSN： 1475-7516

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    <jats:title>Abstract</jats:title> <jats:p>We show that a hybrid inflation model with multiple waterfall fields can result in the formation of primordial black holes (PBHs) with an astrophysical size, by using an advanced algorithm to follow the stochastic dynamics of the waterfall fields. This is in contrast to the case with a single waterfall field, where the wavelength of density perturbations is usually too short to form PBHs of the astrophysical scale (or otherwise PBHs are overproduced and the model is ruled out) unless the inflaton potential is tuned. In particular, we demonstrate that PBHs with masses of order 10<jats:sup>20</jats:sup> g can form after hybrid inflation consistently with other cosmological observations if the number of waterfall fields is about 5 for the case of instantaneous reheating. Observable gravitational waves are produced from the second-order effect of large curvature perturbations as well as from the dynamics of texture or global defects that form after the waterfall phase transition. </jats:p>

  25. Can baryon asymmetry be explained by a large initial value before inflation? Peer-reviewed

    Kai Murai, Fuminobu Takahashi, Masaki Yamada, Wen Yin

    Physical Review D　108　(8)　2023/10/18

    Publisher: American Physical Society (APS)

    DOI： 10.1103/physrevd.108.083518 　

    ISSN： 2470-0010

    eISSN： 2470-0029

  26. Quantum decay of scalar and vector boson stars and oscillons into gravitons Peer-reviewed

    Kazunori Nakayama, Fuminobu Takahashi, Masaki Yamada

    Journal of Cosmology and Astroparticle Physics　2023/08/01

    DOI： 10.1088/1475-7516/2023/08/058 　

    ISSN： 1475-7516

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    <jats:title>Abstract</jats:title><jats:p>We point out that a soliton such as an oscillon or boson star inevitably decays into gravitons through gravitational interactions. These decay processes exist even if there are no apparent self-interactions of the constituent field, scalar or vector, since they are induced by gravitational interactions. Hence, our results provide a strict upper limit on the lifetime of oscillons and boson stars including the dilute axion star. We also calculate the spectrum of the graviton background from decay of solitons.</jats:p>

  27. Primordial black hole formation in hybrid inflation Peer-reviewed

    Yuichiro Tada, Masaki Yamada

    Physical Review D　107　(12)　2023/06/30

    Publisher: American Physical Society (APS)

    DOI： 10.1103/PhysRevD.107.123539 　

    ISSN： 2470-0010

    eISSN： 2470-0029

  28. Axion dark matter from first-order phase transition, and very high energy photons from GRB 221009A Peer-reviewed

    Shota Nakagawa, Fuminobu Takahashi, Masaki Yamada, Wen Yin

    Physics Letters B　839　137824-137824　2023/04

    Publisher: Elsevier BV

    DOI： 10.1016/j.physletb.2023.137824 　

    ISSN： 0370-2693

  29. Cosmic F- and D-strings from pure Yang–Mills theory Peer-reviewed

    Masaki Yamada, Kazuya Yonekura

    Physics Letters B　838　2023/03

    DOI： 10.1016/j.physletb.2023.137724 　

    ISSN： 0370-2693

  30. Formation of hot spots around small primordial black holes Peer-reviewed

    Minxi He, Kazunori Kohri, Kyohei Mukaida, Masaki Yamada

    Journal of Cosmology and Astroparticle Physics　2023　(01)　027-027　2023/01/20

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2023/01/027 　

    ISSN： 1475-7516

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    <jats:title>Abstract</jats:title> <jats:p>In this paper, we investigate the thermalization of Hawking radiation from primordial black holes (PBHs) in the early Universe, taking into account the interference effect on thermalization of high energy particles, known as Landau-Pomeranchuk-Migdal (LPM) effect. Small PBHs with masses ≲ 10<jats:sup>9</jats:sup> g completely evaporate before the big bang nucleosynthesis (BBN). The Hawking radiation emitted from these PBHs heats up the ambient plasma with temperature lower than the Hawking temperature, which results in a non-trivial temperature profile around the PBHs, namely a hot spot surrounding a PBH with a broken power-law tail. We find that the hot spot has a core with a radius much larger than the black hole horizon and its highest temperature is independent of the initial mass of the PBH such as 2 × 10<jats:sup>9</jats:sup> GeV × (<jats:italic>α</jats:italic>/0.1)<jats:sup>19/3</jats:sup>, where <jats:italic>α</jats:italic> generically represents the fine-structure constants. We also briefly discuss the implications of the existence of the hot spot for phenomenology.</jats:p>

  31. Wash-in leptogenesis after axion inflation Peer-reviewed

    Valerie Domcke, Kohei Kamada, Kyohei Mukaida, Kai Schmitz, Masaki Yamada

    Journal of High Energy Physics　2023/01/12

    DOI： 10.1007/JHEP01(2023)053 　

  32. Gravitational production of dark photon dark matter with mass generated by the Higgs mechanism Peer-reviewed

    Takanori Sato, Fuminobu Takahashi, Masaki Yamada

    Journal of Cosmology and Astroparticle Physics　2022　(08)　022-022　2022/08/01

    Publisher: IOP Publishing

    DOI： 10.1088/1475-7516/2022/08/022 　

    ISSN： 1475-7516

    eISSN： 1475-7516

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    Abstract We study the gravitational production of dark photon dark matter during inflation, when dark photons acquire mass by the Higgs mechanism. In the previous study, it was assumed that the dark photon has a Stückelberg mass, or a mass generated by the Higgs mechanism with a sufficiently heavy Higgs boson. In this paper we consider a case in which the Higgs boson is not fully decoupled; the Higgs field changes its vacuum expectation value after inflation. Then, the dark photon mass also changes with time after inflation, and the time evolution of the longitudinal mode is different from the case with a Stückelberg mass. Consequently, the spectrum of the dark photon energy density can have two peaks at an intermediate scale and a small scale. We show that the dark photon can explain the dark matter if its current mass is larger than 6 μeV × (HI/1014 GeV)-4 and smaller than 0.8 GeV × (HI/1014 GeV)-3/2, with HI being the Hubble parameter during inflation. A higher mass is required if one considers a larger gauge coupling constant. The result for the Stückelberg mass can be reproduced in the limit of a small gauge coupling constant. We also comment on the constraints set by various conjectures in quantum gravity theory.

  33. Semiclassical analysis of axion-assisted and axion-driven pair production Peer-reviewed

    Hiroyuki Kitamoto, Masaki Yamada

    Journal of High Energy Physics　2022　(6)　2022/06

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1007/jhep06(2022)103 　

    ISSN： 1029-8479

    eISSN： 1029-8479

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    <jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>We study the pair production of fermions in a time dependent axion background with and without an electric background. We construct the adiabatic mode functions which incorporate the gauge field and the axion velocity dependence of the dispersion relation. The semiclassical approach using this adiabatic basis shows two types of pair production. One is <jats:italic>axion-assisted pair production</jats:italic>: the presence of the axion velocity gives enhancement and interference effects on the pair production driven by the electric field. The other is <jats:italic>axion-driven pair production</jats:italic>: the time variation of the axion velocity causes the pair production even though the electric field is absent.</jats:p>

  34. Baryon asymmetric Universe from spontaneous CP violation Peer-reviewed

    Kohei Fujikura, Yuichiro Nakai, Ryosuke Sato, Masaki Yamada

    Journal of High Energy Physics　2022　(4)　2022/04

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1007/JHEP04(2022)105 　

    eISSN： 1029-8479

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    Abstract Spontaneous CP violation, such as the Nelson-Barr (NB) mechanism, is an attractive scenario for addressing the strong CP problem while realizing the observed phase of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix. However, not only the CKM phase but also the baryon asymmetric Universe requires sources of CP violation. In this study, we show that a supersymmetric NB mechanism can naturally accommodate the Affleck-Dine (AD) baryogenesis within a CP-invariant Lagrangian. The model provides flat directions associated with new heavy quarks. Focusing on one of the directions, we find that the correct baryon asymmetry is obtained with a sufficiently low reheating temperature which does not cause the gravitino problem. Some parameter space is consistent with the gravitino dark matter. We assess radiative corrections to the strong CP phase induced by gauge-mediated supersymmetry breaking and CP-violating heavy fields and show that the strong CP problem is solved in a viable parameter space where the visible sector supersymmetric particles must be lighter than $$ \mathcal{O} $$(100) TeV. Even in the case that they are heavier than the TeV scale, our model predicts the neutron electric dipole moment within the reach of the near future experiments. Our model addresses the electroweak naturalness problem, strong CP problem, baryon asymmetric Universe, and dark matter. Then, the model may give a new compelling paradigm of physics beyond the Standard Model.

  35. A natural and simple UV completion of the QCD axion model Peer-reviewed

    Masaki Yamada, Tsutomu T. Yanagida

    Physics Letters B　816　136267-136267　2021/05

    Publisher: Elsevier BV

    DOI： 10.1016/j.physletb.2021.136267 　

    ISSN： 0370-2693

  36. Trapping effect for QCD axion dark matter Peer-reviewed

    Shota Nakagawa, Fuminobu Takahashi, Masaki Yamada

    Journal of Cosmology and Astroparticle Physics　2021　(05)　062-062　2021/05/01

    DOI： 10.1088/1475-7516/2021/05/062 　

    ISSN： 1475-7516

    eISSN： 1475-7516

  37. Gravitational waves and dark radiation from dark phase transition: Connecting NANOGrav pulsar timing data and hubble tension Peer-reviewed

    Yuichiro Nakai, Motoo Suzuki, Fuminobu Takahashi, Masaki Yamada

    Physics Letters B　816　136238-136238　2021/05

    Publisher: Elsevier BV

    DOI： 10.1016/j.physletb.2021.136238 　

    ISSN： 0370-2693

  38. What if ALP dark matter for the XENON1T excess is the inflaton Peer-reviewed

    Fuminobu Takahashi, Masaki Yamada, Wen Yin

    Journal of High Energy Physics　2021　(1)　2021/01

    DOI： 10.1007/jhep01(2021)152 　

    ISSN： 1029-8479

    eISSN： 1029-8479

  39. Cosmic perturbations, baryon asymmetry, and dark matter from the minimal supersymmetric standard model Peer-reviewed

    Keisuke Harigaya, Masaki Yamada

    Physical Review D　102　(12)　2020/12/01

    Publisher: American Physical Society (APS)

    DOI： 10.1103/PhysRevD.102.121301 　

    ISSN： 2470-0010

    eISSN： 2470-0029

  40. Strongly-interacting massive particle and dark photon in the era of the intensity frontier Peer-reviewed

    Kamada, A., Yamada, M., Yanagida, T.T.

    Physical Review D　102　(7)　2020

    Publisher: American Physical Society (APS)

    DOI： 10.1103/PhysRevD.102.075001 　

    ISSN： 2470-0010

    eISSN： 2470-0029

  41. Unification for darkly charged dark matter Peer-reviewed

    Kamada, A., Yamada, M., Yanagida, T.T.

    Physical Review D　102　(1)　2020

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.102.015012 　

    ISSN： 2470-0010

  42. Four-volume cutoff measure of the multiverse Peer-reviewed

    Vilenkin, A., Yamada, M.

    Physical Review D　101　(4)　2020

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.101.043520 　

    ISSN： 2470-0010

  43. A more attractive scheme for radion stabilization and supercooled phase transition Peer-reviewed

    Fujikura, K., Nakai, Y., Yamada, M.

    Journal of High Energy Physics　2020　(2)　2020

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1007/JHEP02(2020)111 　

    ISSN： 1029-8479

  44. Fundamental forces and scalar field dynamics in the early universe Peer-reviewed

    Kusenko, A., Takhistov, V., Yamada, M., Yamazaki, M.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics　804　135369-135369　2020

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.physletb.2020.135369 　

    ISSN： 0370-2693

  45. Charged black holes in non-linear Q-clouds with O(3) symmetry Peer-reviewed

    Hong, J.-P., Suzuki, M., Yamada, M.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics　803　135324-135324　2020

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.physletb.2020.135324 　

    ISSN： 0370-2693

  46. Vacuum decay in real time and imaginary time formalisms Peer-reviewed

    Mark P. Hertzberg, Masaki Yamada

    Physical Review D　100　(1)　2019/07

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/physrevd.100.016011 　

    ISSN： 2470-0010

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    We analyze vacuum tunneling in quantum field theory in a general formalism by using the Wigner representation. In the standard instanton formalism, one usually approximates the initial false vacuum state by an eigenstate of the field operator, imposes Dirichlet boundary conditions on the initial field value, and evolves in imaginary time. This approach does not have an obvious physical interpretation. However, an alternative approach does have a physical interpretation: in quantum field theory, tunneling can happen via classical dynamics, seeded by initial quantum fluctuations in both the field and its momentum conjugate, which was recently implemented in Ref. [1]. We show that the Wigner representation is a useful framework to calculate and understand the relationship between these two approaches. We find there are two, related, saddle point approximations for the path integral of the tunneling process: one corresponds to the instanton solution in imaginary time and the other one corresponds to classical dynamics from initial quantum fluctuations in real time. The classical approximation for the dynamics of the latter process is justified only in a system with many degrees of freedom, as can appear in field theory due to high occupancy of nucleated bubbles, while it is not justified in single particle quantum mechanics, as we explain. We mention possible applications of the real time formalism, including tunneling when the instanton vanishes, or when the imaginary time contour deformation is not possible, which may occur in cosmological settings.

  47. Anthropic bound on dark radiation and its implications for reheating Peer-reviewed

    Takahashi, F., Yamada, M.

    Journal of Cosmology and Astroparticle Physics　2019　(7)　001-001　2019

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2019/07/001 　

    ISSN： 1475-7516

  48. Self-interacting dark matter with a vector mediator: kinetic mixing with the U(1)(B−L)3 gauge boson Peer-reviewed

    Kamada, A., Yamada, M., Yanagida, T.T.

    Journal of High Energy Physics　2019　(3)　2019

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1007/JHEP03(2019)021 　

    ISSN： 1029-8479

  49. Unification of the standard model and dark matter sectors in [SU(5) × U(1)]4 Peer-reviewed

    Kamada, A., Yamada, M., Yanagida, T.T.

    Journal of High Energy Physics　2019　(7)　2019

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1007/JHEP07(2019)180 　

    ISSN： 1029-8479

  50. Light majoron cold dark matter from topological defects and the formation of boson stars Peer-reviewed

    Reig, M., Valle, J.W.F., Yamada, M.

    Journal of Cosmology and Astroparticle Physics　2019　(9)　029-029　2019

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2019/09/029 　

    ISSN： 1475-7516

  51. Constraints on non-minimal coupling from quantum cosmology Peer-reviewed

    Wang, S.-J., Yamada, M., Vilenkin, A.

    Journal of Cosmology and Astroparticle Physics　2019　(8)　025-025　2019

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2019/08/025 　

    ISSN： 1475-7516

  52. Dark matter production during the thermalization era Peer-reviewed

    Harigaya, K., Mukaida, K., Yamada, M.

    Journal of High Energy Physics　2019　(7)　2019

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1007/JHEP07(2019)059 　

    ISSN： 1029-8479

  53. Tunneling wave function of the universe. II. the backreaction problem Peer-reviewed

    Vilenkin, A., Yamada, M.

    Physical Review D　99　(6)　2019

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.99.066010 　

    ISSN： 2470-0010

  54. Isocurvature perturbations of dark energy and dark matter from the Swampland conjecture Peer-reviewed

    Matsui, H., Takahashi, F., Yamada, M.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics　789　387-392　2019

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.physletb.2018.12.055 　

    ISSN： 0370-2693

  55. Compact objects as the catalysts for vacuum decays Peer-reviewed

    Oshita, N., Yamada, M., Yamaguchi, M.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics　791　149-155　2019

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.physletb.2019.02.032 　

    ISSN： 0370-2693

  56. Classical nonrelativistic effective field theory and the role of gravitational interactions Peer-reviewed

    Eby, J., Mukaida, K., Takimoto, M., Wijewardhana, L.C.R., Yamada, M.

    Physical Review D　99　(12)　2019

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.99.123503 　

    ISSN： 2470-0010

  57. Tunneling wave function of the universe Peer-reviewed

    Vilenkin, A., Yamada, M.

    Physical Review D　98　(6)　2018

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.98.066003 　

    ISSN： 2470-0010

  58. Unified origin of axion and monopole dark matter, and solution to the domain-wall problem Peer-reviewed

    Sato, R., Takahashi, F., Yamada, M.

    Physical Review D　98　(4)　2018

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.98.043535 　

    ISSN： 2470-0010

  59. CMB spectral distortions from black holes formed by vacuum bubbles Peer-reviewed

    Deng, H., Vilenkin, A., Yamada, M.

    Journal of Cosmology and Astroparticle Physics　2018　(7)　059-059　2018

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2018/07/059 　

    ISSN： 1475-7516

  60. Hessian eigenvalue distribution in a random Gaussian landscape Peer-reviewed

    Yamada, M., Vilenkin, A.

    Journal of High Energy Physics　2018　(3)　2018

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1007/JHEP03(2018)029 　

    ISSN： 1029-8479

  61. Inflation in random landscapes with two energy scales Peer-reviewed

    Blanco-Pillado, J.J., Vilenkin, A., Yamada, M.

    Journal of High Energy Physics　2018　(2)　2018

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1007/JHEP02(2018)130 　

    ISSN： 1029-8479

  62. Adiabatic suppression of the axion abundance and isocurvature due to coupling to hidden monopoles Peer-reviewed

    Kawasaki, M., Takahashi, F., Yamada, M.

    Journal of High Energy Physics　2018　(1)　2018

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1007/JHEP01(2018)053 　

    ISSN： 1029-8479

  63. False vacuum decay catalyzed by black holes Peer-reviewed

    Mukaida, K., Yamada, M.

    Physical Review D　96　(10)　2017

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.96.103514 　

    ISSN： 2470-0010

  64. Entanglement entropy and decoupling in the Universe Peer-reviewed

    Nakai, Y., Shiba, N., Yamada, M.

    Physical Review D　96　(12)　2017

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.96.123518 　

    ISSN： 2470-0010

  65. Inflation in multi-field random Gaussian landscapes Peer-reviewed

    Masoumi, A., Vilenkin, A., Yamada, M.

    Journal of Cosmology and Astroparticle Physics　2017　(12)　035-035　2017

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2017/12/035 　

    ISSN： 1475-7516

  66. Initial conditions for slow-roll inflation in a random Gaussian landscape Peer-reviewed

    Masoumi, A., Vilenkin, A., Yamada, M.

    Journal of Cosmology and Astroparticle Physics　2017　(7)　003-003　2017

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2017/07/003 　

    ISSN： 1475-7516

  67. Visible and dark matter genesis through the Affleck-Dine mechanism Peer-reviewed

    Masaki Yamada

    PhD Thesis　2016/03/24

    DOI： 10.15083/00073308 　

  68. High-scale SUSY from an R-invariant new inflation in the landscape Peer-reviewed

    Kawasaki, M., Yamada, M., Yanagida, T.T., Yokozaki, N.

    Physical Review D　93　(5)　2016

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.93.055022 　

    ISSN： 2470-0010

  69. Thermalization process after inflation and effective potential of scalar field Peer-reviewed

    Mukaida, K., Yamada, M.

    Journal of Cosmology and Astroparticle Physics　2016　(2)　003-003　2016

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2016/02/003 　

    ISSN： 1475-7516

  70. SIMP from a strong U(1) gauge theory with a monopole condensation Peer-reviewed

    Kamada, A., Yamada, M., Yanagida, T.T., Yonekura, K.

    Physical Review D　94　(5)　2016

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.94.055035 　

    ISSN： 2470-0010

  71. Can thermal inflation be consistent with baryogenesis in gauge-mediated SUSY breaking models? Peer-reviewed

    Hayakawa, T., Kawasaki, M., Yamada, M.

    Physical Review D　93　(6)　2016

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.93.063529 　

    ISSN： 2470-0010

  72. Diphoton excess from hidden U(1) gauge symmetry with large kinetic mixing Peer-reviewed

    Takahashi, F., Yamada, M., Yokozaki, N.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics　760　486-493　2016

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.physletb.2016.07.013 　

    ISSN： 0370-2693

  73. Charged Q-ball dark matter from B and L direction Peer-reviewed

    Hong, J.-P., Kawasaki, M., Yamada, M.

    Journal of Cosmology and Astroparticle Physics　2016　(8)　053-053　2016

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2016/08/053 　

    ISSN： 1475-7516

  74. Cosmology with a heavy Polonyi field Peer-reviewed

    Harigaya, K., Hayakawa, T., Kawasaki, M., Yamada, M.

    Journal of Cosmology and Astroparticle Physics　2016　(6)　015-015　2016

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2016/06/015 　

    ISSN： 1475-7516

  75. Suppressing the QCD axion abundance by hidden monopoles Peer-reviewed

    Kawasaki, M., Takahashi, F., Yamada, M.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics　753　677-681　2016

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.physletb.2015.12.075 　

    ISSN： 0370-2693

  76. Spontaneous baryogenesis from asymmetric inflaton Peer-reviewed

    Takahashi, F., Yamada, M.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics　756　216-220　2016

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.physletb.2016.03.020 　

    ISSN： 0370-2693

  77. Diphoton excess as a hidden monopole Peer-reviewed

    Yamada, M., Yanagida, T.T., Yonekura, K.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics　759　459-463　2016

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.physletb.2016.06.005 　

    ISSN： 0370-2693

  78. Affleck-Dine leptogenesis and its backreaction to inflaton dynamics Peer-reviewed

    Yamada, M.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics　754　208-213　2016

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.physletb.2015.12.080 　

    ISSN： 0370-2693

  79. Charged Q -balls in gauge mediated SUSY breaking models Peer-reviewed

    Hong, J.-P., Kawasaki, M., Yamada, M.

    Physical Review D - Particles, Fields, Gravitation and Cosmology　92　(6)　2015

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.92.063521 　

    ISSN： 1550-7998

  80. Gravitational wave signals from short-lived topological defects in the MSSM Peer-reviewed

    Kamada, A., Yamada, M.

    Journal of Cosmology and Astroparticle Physics　2015　(10)　021-021　2015

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2015/10/021 　

    ISSN： 1475-7516

  81. Strongly broken Peccei-Quinn symmetry in the early Universe Peer-reviewed

    Takahashi, F., Yamada, M.

    Journal of Cosmology and Astroparticle Physics　2015　(10)　010-010　2015

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2015/10/010 　

    ISSN： 1475-7516

  82. Observable dark radiation from a cosmologically safe QCD axion Peer-reviewed

    Kawasaki, M., Yamada, M., Yanagida, T.T.

    Physical Review D - Particles, Fields, Gravitation and Cosmology　91　(12)　2015

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.91.125018 　

    ISSN： 1550-7998

  83. Affleck-Dine baryogenesis after D -term inflation and solutions to the baryon-dark matter coincidence problem Peer-reviewed

    Kawasaki, M., Yamada, M.

    Physical Review D - Particles, Fields, Gravitation and Cosmology　91　(8)　2015

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.91.083512 　

    ISSN： 1550-7998

  84. Gravitational waves as a probe of the SUSY scale Peer-reviewed

    Kamada, A., Yamada, M.

    Physical Review D - Particles, Fields, Gravitation and Cosmology　91　(6)　2015

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.91.063529 　

    ISSN： 1550-7998

  85. Cosmologically safe QCD axion as a present from extra dimension Peer-reviewed

    Kawasaki, M., Yamada, M., Yanagida, T.T.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics　750　12-16　2015

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.physletb.2015.08.043 　

    ISSN： 0370-2693

  86. Solution to the baryon-dark-matter coincidence problem in the constrained minimal supersymmetric model with a 126-GeV Higgs boson Peer-reviewed

    Kamada, A., Kawasaki, M., Yamada, M.

    Physical Review D - Particles, Fields, Gravitation and Cosmology　91　(8)　2015

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.91.081301 　

    ISSN： 1550-7998

  87. Decay rates of Gaussian-type I-balls and Bose-enhancement effects in 3 + 1 dimensions Peer-reviewed

    Kawasaki, M., Yamada, M.

    Journal of Cosmology and Astroparticle Physics　2014　(2)　001-001　2014

    Publisher: {IOP} Publishing

    DOI： 10.1088/1475-7516/2014/02/001 　

    ISSN： 1475-7516

  88. Affleck-Dine baryogenesis and dark matter production after high-scale inflation Peer-reviewed

    Harigaya, K., Kamada, A., Kawasaki, M., Mukaida, K., Yamada, M.

    Physical Review D - Particles, Fields, Gravitation and Cosmology　90　(4)　2014

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.90.043510 　

    ISSN： 1550-7998

  89. Opening the window to the cogenesis with Affleck-Dine mechanism in gravity mediation Peer-reviewed

    Kamada, A., Kawasaki, M., Yamada, M.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics　719　(1-3)　9-13　2013

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.physletb.2013.01.017 　

    ISSN： 0370-2693

  90. Q-ball decay rates into gravitinos and quarks Peer-reviewed

    Kawasaki, M., Yamada, M.

    Physical Review D - Particles, Fields, Gravitation and Cosmology　87　(2)　2013

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevD.87.023517 　

    ISSN： 1550-7998

  91. Revisiting the gravitino dark matter and baryon asymmetry from Q-ball decay in gauge mediation Peer-reviewed

    Kasuya, S., Kawasaki, M., Yamada, M.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics　726　(1-3)　1-7　2013

    Publisher: Elsevier {BV}

    DOI： 10.1016/j.physletb.2013.08.008 　

    ISSN： 0370-2693

Show all ︎Show first 5

Misc. 2

  1. Snowmass Theory Frontier: Astrophysics and Cosmology

    Daniel Green, Joshua T. Ruderman, Benjamin R. Safdi, Jessie Shelton, Ana Achúcarro, Peter Adshead, Yashar Akrami, Masha Baryakhtar, Daniel Baumann, Asher Berlin, Nikita Blinov, Kimberly K. Boddy, Malte Buschmann, Giovanni Cabass, Robert Caldwell, Emanuele Castorina, Thomas Y. Chen, Xingang Chen, William Coulton, Djuna Croon, Yanou Cui, David Curtin, Francis-Yan Cyr-Racine, Christopher Dessert, Keith R. Dienes, Patrick Draper, Peizhi Du, Sebastian A. R. Ellis, Rouven Essig, Raphael Flauger, Chee Sheng Fong, Joshua W. Foster, Jacopo Fumagalli, Keisuke Harigaya, Shunsaku Horiuchi, Mikhail M. Ivanov, Yonatan Kahn, Simon Knapen, Rebecca K. Leane, Hayden Lee, Erik W. Lentz, Matthew Lewandowski, Mariangela Lisanti, Andrew J. Long, Marilena Loverde, Azadeh Maleknejad, Liam McAllister, Samuel D. McDermott, Robert McGehee, P. Daniel Meerburg, Joel Meyers, Azadeh Moradinezhad Dizgah, Moritz Münchmeyer, Nadav Joseph Outmezguine, Enrico Pajer, Gonzalo A. Palma, Aditya Parikh, Jong-Chul Park, Annika H. G. Peter, Guilherme L. Pimentel, Sébastien Renaux-Petel, Nicholas L. Rodd, Bibhushan Shakya, Gary Shiu, Eva Silverstein, Marko Simonovic, Rajeev Singh, Charlotte Sleight, Volodymyr Takhistov, Philip Tanedo, Massimo Taronna, Brooks Thomas, Natalia Toro, Yu-Dai Tsai, Edoardo Vitagliano, Mark Vogelsberger, Benjamin Wallisch, Benjamin D. Wandelt, Risa H. Wechsler, Christoph Weniger, W. L. Kimmy Wu, Weishuang Linda Xu, Masaki Yamada, Hai-Bo Yu, Zhengkang Zhang, Yi-Ming Zhong, Kathryn Zurek

    2022/09/14

    More details Close

    We summarize progress made in theoretical astrophysics and cosmology over the past decade and areas of interest for the coming decade. This Report is prepared as the TF09 "Astrophysics and Cosmology" topical group summary for the Theory Frontier as part of the Snowmass 2021 process.

  2. Early-Universe Model Building

    Pouya Asadi, Saurabh Bansal, Asher Berlin, Raymond T. Co, Djuna Croon, Yanou Cui, David Curtin, Francis-Yan Cyr-Racine, Hooman Davoudiasl, Luigi Delle Rose, Marco Drewes, Jeff A. Dror, Gilly Elor, Oliver Gould, Keisuke Harigaya, Saniya Heeba, Yonit Hochberg, Anson Hook, Seyda Ipek, Eric Kuflik, Andrew J. Long, Robert McGehee, Nadav Joseph Outmezguine, Giuliano Panico, Vivian Poulin, Josef Pradler, Katelin Schutz, Nausheen R. Shah, Bibhushan Shakya, Michael Shamma, Brian Shuve, Juri Smirnov, Yuhsin Tsai, Jessica Turner, Jorinde van de Vis, Christopher B. Verhaaren, Neal Weiner, Masaki Yamada, Tevong You, Hai-Bo Yu

    2022/03/13

    More details Close

    Theoretical investigations into the evolution of the early universe are an essential part of particle physics that allow us to identify viable extensions to the Standard Model as well as motivated parameter space that can be probed by various experiments and observations. In this white paper, we review particle physics models of the early universe. First, we outline various models that explain two essential ingredients of the early universe (dark matter and baryon asymmetry) and those that seek to address current observational anomalies. We then discuss dynamics of the early universe in models of neutrino masses, axions, and several solutions to the electroweak hierarchy problem. Finally, we review solutions to naturalness problems of the Standard Model that employ cosmological dynamics.

Presentations 58

  1. Cosmic strings, Dark Matter, and Gravitational Wave Signatures from Pure Yang-Mills Theory International-presentation Invited

    Masaki Yamada

    Workshop on Particle Physics and Cosmology, Busan 2023　2023/12/18

  2. Cosmic strings, Dark Matter, and Gravitational Wave Signatures from Pure Yang-Mills Theory International-presentation Invited

    Masaki Yamada

    Gravitational Wave Probes of Physics Beyond the Standard Model (GWPBSM)　2023/11/09

  3. Cascades of high-energy particles and non-thermal DM production in the pre-thermal phase International-presentation Invited

    Masaki Yamada

    Korea - Japan joint workshop on Particle Physics, Cosmology, and Gravity　2023/05/17

  4. Cascades of high-energy particles and non-thermal DM production in the pre-thermal phase International-presentation Invited

    Masaki Yamada

    Dark Matter as a portal to New Physics 2023　2023/01/09

  5. 熱い宇宙のはじまり ~ 素粒子標準模型を用いて宇宙の熱化を解明する ~ Invited

    山田將樹

    物理科学の最前線　2022/11/11

  6. Leptoflavorgenesis: baryon asymmetry of the Universe from lepton flavor violation International-presentation Invited

    Masaki Yamada

    New observational windows on the high-scale origin of matter-antimatter asymmetry　2022/01/13

  7. Cosmic Birefringence Triggered by Dark Matter Domination International-presentation Invited

    Masaki Yamada

    Cambridge High Energy Workshop 2021 - Axion Physics　2021/07/30

  8. Present status of axion theories and searches International-presentation Invited

    Masaki Yamada

    Kashiwa Dark Matter Symposium 2020　2020/11/19

  9. NANOGrav and first-order phase transition in the early Universe International-presentation Invited

    Masaki Yamada

    KEK-PH + KEK-Cosmo Gravitational Wave (GW)　2020/11/04

  10. Inflation in random Gaussian landscapes International-presentation Invited

    Masaki Yamada

    North-East Cosmology Workshop 2018　2018/06/17

  11. Entanglement Entropy and Decoupling in the Universe International-presentation Invited

    山田將樹

    Workshop on Beyond Standard Model and the Early Universe　2017/10

  12. Affleck-Dine baryogenesis after D-term inflation and a solution to the baryon-DM coincidence problem International-presentation

    山田將樹

    Physics at the LHC and beyond, DESY theory workshop　2015/08

  13. ホーキング放射の熱化とブラックホール周りの熱分布について

    山田將樹

    日本物理学会第79回年次大会　2024/09/17

  14. Cosmic strings, Dark Matter, and Gravitational Wave Signatures from Pure Yang-Mills Theory

    Masaki Yamada

    2024/03/05

  15. pure Yang-Mills theoryにおけるcosmic (super)stringとダークマターの生成

    山田將樹

    日本物理学会 2024年春季大会　2024/03/21

  16. GUTハイブリッドインフレーションとモノポール問題

    山田將樹

    日本物理学会　2023/09/17

  17. 荷電レプトンフレーバー対称性の破れを用いた宇宙のバリオン数生成機構

    山田將樹

    基研研究会 素粒子物理学の進展２０２２　2022/08/29

  18. Cosmic F- and D-strings from pure Yang-Mills theory International-presentation

    Masaki Yamada

    The 15th Asia Pacific Physics Conference　2022/08/23

  19. Spherically symmetric scalar hair for charged black hole

    Masaki Yamada

    2021/11/08

  20. Spherically symmetric scalar hair for charged black hole

    Masaki Yamada

    2021/09/16

  21. Cosmic Birefringence Triggered by Dark Matter Domination

    Masaki Yamada

    2021/09/06

  22. Cosmic Birefringence Triggered by Dark Matter Domination International-presentation

    Masaki Yamada

    The XXVIII International Conference on Supersymmetry and Unification of Fundamental Interactions (SUSY 2021)　2021/08/27

  23. Cosmic Birefringence Triggered by Dark Matter Domination International-presentation

    Masaki Yamada

    PASCOS 2021, the 26th International Symposium on Particle Physics, String Theory, and Cosmology　2021/06/14

  24. Cosmic Birefringence Triggered by Dark Matter Domination International-presentation

    Masaki Yamada

    PPC 2021: XIV International Workshop on Interconnections between Particle Physics and Cosmology　2021/05/21

  25. Cosmic Birefringence Triggered by Dark Matter

    Masaki Yamada

    2021/02/12

  26. What is dark matter? - XENON1T excess from axion dark matter -

    Masaki Yamada

    The 5th FRIS Retreat　2020/11/26

  27. Unification for Darkly Charged Dark Matter International-presentation

    Masaki Yamada

    KEK-PH + KEK-Cosmo (Dark Matter)　2020/10/13

  28. Unification for the Darkly Charged Dark Matter

    山田將樹

    日本物理学会 2020年秋季大会　2020/09/15

  29. Unification for Darkly Charged Dark Matter

    山田將樹

    基研研究会「素粒子物理学の進展2020」　2020/09/03

  30. Unification for Darkly Charged Dark Matter International-presentation

    Masaki Yamada

    Cosmology from Home 2020　2020/08/26

  31. Unification of the SM and DM in [SU(5)*U(1)]^4 GUT International-presentation

    山田將樹

    2019 Meeting of the Division of Particles & Fields of the American Physical Society (DPF2019)　2019/08/01

  32. Unification of the SM and DM in [SU(5)]*U(1)]^4 GUT International-presentation

    山田將樹

    27th International Conference on Supersymmetry and Unification of Fundamental Interactions (SUSY2019)　2019/05

  33. Non-relativistic effective field theory of scalar field and longevity of condensates International-presentation

    山田將樹

    Identification of Dark Matter 2018　2018/07

  34. Affleck-Dine leptogenesis and its backreaction to inflaton dynamics International-presentation

    山田將樹

    Revealing the history of the Universe with underground particle and nuclear research 2016　2016/05

  35. Spontaneous baryogenesis from asymmetric inflaton

    山田將樹

    日本物理学会 第71回年次大会　2016/03

  36. Visible and dark matter genesis through the Affleck-Dine mechanism

    山田將樹

    宇宙線研究所修士博士発表会　2016/02

  37. Spontaneous Baryogenesis via Four-Fermi Operator International-presentation

    山田將樹

    KEK-ph　2016/02

  38. Cosmologically safe QCD axion as a present from extra dimension

    山田將樹

    基研研究会 素粒子物理学の進展2015 (PPP2015)　2015/09

  39. Cosmologically safe QCD axion as a present from extra dimension International-presentation

    山田將樹

    RESCEU APCosPA Summer School on Cosmology and Particle Astrophysics　2015/08

  40. 重力波で超対称性のスケールを探る

    山田將樹

    日本物理学会 第70回年次大会　2015/03

  41. Gravitational waves as a probe of supersymmetric scale'

    山田將樹

    宇宙線研究所修士博士発表会　2015/02

  42. 宇宙の再加熱時期における暗黒物質の生成

    山田將樹

    第27回 理論懇シンポジウム 理論天文学宇宙物理学と境界領域　2014/12

  43. Dark matter production in late time reheating International-presentation

    山田將樹

    10th Conference in the Symposium on Cosmology and Particle Astrophysics Series (CosPA 2014)　2014/12

  44. Dark matter production in late time reheating'

    山田將樹

    第二回 松江現象論研究会　2014/11

  45. Gravitational waves as a probe of supersymmetric scale International-presentation

    山田將樹

    The 24th Workshop on General Relativity and Gravitation (JGRG24)　2014/11

  46. Dark matter production in late time reheating' International-presentation

    山田將樹

    KEK Theory Meeting on Particle Physics Phenomenology (KEK-ph 2014)　2014/10

  47. 低い再加熱温度における暗黒物質生成について

    山田將樹

    日本物理学会 2014秋季大会　2014/09

  48. Gravitational waves as a probe of supersymmetric scale' International-presentation

    山田將樹

    Summer Institute 2014 (SI 2014)　2014/08

  49. Gravitational waves as a probe of supersymmetric scale International-presentation

    山田將樹

    RESCEU APCosPA Summer School on Cosmology and Particle Astrophysics　2014/08

  50. 重力波で超対称性のスケールを探る

    山田將樹

    基研研究会 素粒子物理学の進展2014 (PPP2014)　2014/07

  51. A solution to the baryon-DM coincidence problem in the mSUGRA/CMSSM model with a 126 GeV Higgs boson International-presentation

    山田將樹

    The 22nd International Conference on Supersymmetry and Unification of Fundamental Interactions (SUSY2014)　2014/07

  52. Dark matter production in late time reheating'

    山田將樹

    宇宙線研究所修士博士発表会　2014/02

  53. Co-genesis of baryon and dark matter from Q-ball decay in anomaly mediation International-presentation

    山田將樹

    The 19th International Symposium on Particles, Strings and Cosmology, (PASCOS 2013)　2013/11

  54. Q-ballのグラビティーノとクォークへの崩壊率と初期宇宙に対する応用

    山田將樹

    日本物理学会 2013年秋季大会, 高知大学 朝倉キャンパス　2013/09

  55. Opening the window to the co-genesis with Affleck-Dine mechanism in gravity mediation' International-presentation

    山田將樹

    The annual International Conference on Particle Physics and Cosmology, (COSMO 2013)　2013/09

  56. Q-ball崩壊からのバリオンとダークマターの共生成

    山田將樹

    基研研究会 素粒子物理学の進展2013　2013/08

  57. gravity mediationにおけるQボール崩壊からのバリオンと暗黒物質の共生成

    山田將樹

    日本物理学会 第68回年次大会　2013/03

  58. Opening the window to the cogenesis with Affleck-Dine mechanism in gravity mediation

    山田將樹

    宇宙線研究所修士博士発表会　2013/02

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Research Projects 8

  1. 初期宇宙のインフレーション後の熱平衡化に関する研究

    山田 將樹

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 若手研究

    Institution: 東北大学

    2023/04/01 - 2027/03/31

  2. A theoretical study of the generation and evolution of light dark matter

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Transformative Research Areas (A)

    Institution: Tohoku University

    2020/11 - 2025/03

  3. 素粒子・原子核および物性理論の応用による初期宇宙の熱史の探求

    山田將樹

    Offer Organization: 日本学術振興会

    System: 卓越研究員事業

    Institution: 東北大学

    2020/01 - 2024/03

  4. 超弦理論から示唆される初期宇宙の進化

    山田 將樹

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業 若手研究

    Category: 若手研究

    Institution: 東北大学

    2021/04/01 - 2023/03/31

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    標準理論の強いCP問題を解決するための有力な機構としてPeccei-Quinn機構が考えられている。しかし、この機構を実現するためには量子的には破れているものの古典的には高精度で保たれているような大局的対称性を導入する必要があり、なぜそのような対称性が存在するのかという理論的な問題がある。これを解決するためのモデルとして余剰次元を考えるものが考えられていたが、その余剰次元のサイズを保つために新たな粒子を導入する必要があるなど、モデルが複雑化する傾向にあった。本研究ではこの大局的対称性を生み出す機構と余剰次元のサイズを保つための機構を、たった一つの相互作用を導入することによって実現できることを示した。さらに対称性の破れの大きさは暗黒物質の観測から示唆されている小さい値を自然に実現することができるため、理論的に微調整の必要のない理想的なモデルとなっている。 一方で、Peccei-Quinn機構はアクシオンと呼ばれる新粒子を予言し、暗黒物質の有力な候補となっている。その存在量はアクシオンが持つポテンシャルに依存する。本研究では、ウィッテン効果を通してアクシオンに時間依存するポテンシャル項を加えて、元々のポテンシャルの天辺付近に強く捉えておいた場合にどのようなことが起こるかを議論した。その結果、断熱抑制効果が働くことによって単純な予想とは逆に存在量が抑制されることを示した。このようなポテンシャルはアクシオンの宇宙論的な問題を解決するために考えられることがあり、そのメカニズムとアクシオンの存在量には密接な関係があることが示された。

  5. Thermal history of the Universe and generation of gravitational waves in physics beyond the Standard Model of particle physics

    Yamada Masaki

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Research Activity Start-up

    Institution: Tohoku University

    2020/09/11 - 2022/03/31

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    The origin of baryon asymmetry is a long-standing mystery in cosmology. One of the possible mechanisms to generate baryon asymmetry is the decay of right-handed neutrinos in the early Universe. In the present study, we have revealed that almost any asymmetry can be converted to baryon asymmetry via the interaction associated with the right-handed neutrinos. This opens a broader possibility for the generation of baryon asymmetry in physics beyond the Standard Model. Moreover, we have discussed theoretical implications of recently reported signals of a dark-matter direct detection experiment and a pulsar-timing array experiment and have pointed out that they are related to other astrophysical observations. These works have provided a new insight into the thermal history of the Universe.

  6. Inflation theory and generation of baryon asymmetry, dark matter, and black holes in the early Universe

    Institution: Massachusetts Institute of Technology

    2019/09 - 2020/04

  7. 物質反物質非対称性の起源と暗黒物質およびインフレーション理論に関する研究

    山田 將樹

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業 特別研究員奨励費 (PD)

    Category: 特別研究員奨励費

    Institution: 東北大学

    2016/04 - 2017/08

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    インフレーション理論は地平線問題や平坦性問題などの宇宙論的な諸問題の解決や、宇宙の構造形成の種の生成などの成功を収め、観測的にも確かな理論である。インフレーションのモデルには様々なものが提案されてきているが、本研究では理論的に他のモチベーションのあるモデルにのみ注目した。特に、超弦理論やその低エネルギー有効理論である超重力理論において自然に実現されるモデルに注目して研究を行った。 超弦理論の低エネルギー有効理論においては、モジュライと呼ばれる軽いスカラー場がO(100)個現れることが知られており、これを用いてインフレーションを引き起こすことができる。このモジュライのポテンシャルは、場の個数が大量にあることから、大数の法則によってガウス性をもつ相関関数によってモデル化されることが期待される。このポテンシャルの統計的性質をで詳細に調べたことにより、垂直方向のスカラー場の質量がインフレーションのエネルギースケールよりも大きくなる条件を明らかにし、自然なパラメータの範囲ではゆらぎの非ガウス性や等曲率揺らぎの値が無視できることを示した。また、ガウス性を持つ相関関数から具体的なポテンシャルの形をランダムに生成する方法を提案した。これによって生成されたポテンシャルを用いて擬真空間のトンネル効果やインフラトンのダイナミクスを解析した結果、複雑な多次元のポテンシャルを用いてもインフレーションの予言は１次元の場合と同様であることを示した。さらに、我々の宇宙の曲率揺らぎの振幅の観測値を自然に再現するためには超対称性の破れのエネルギースケールの値に対して条件がつくことを示した。

  8. 宇宙における物質反物質非対称性の起源の問題および暗黒物質に関する研究

    山田 將樹

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業 特別研究員奨励費 (DC1)

    Category: 特別研究員奨励費

    Institution: 東京大学

    2013/04 - 2016/03

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    宇宙背景放射の温度ゆらぎの観測によってインフレーション理論の正当性はほぼ確立したが、インフレーションからビッグバン元素合成の時代までの宇宙はどのような歴史をたどったのかという疑問は初期宇宙論の一つの大きな問題として残されている。 インフレーションはインフラトンと呼ばれるスカラー場のポテンシャルエネルギーによって引き起こされると考えられている。インフレーションからビッグバン宇宙に接続するためにはインフラトンが輻射に崩壊する必要があるが、この輻射が熱化するプロセスを詳細に研究した。これにより、完全に熱化するまでの時間がこれまで考えられてきたものよりも非常に長いことを発見し、結果として宇宙の最高温度はこれまでは高く見積もられすぎていたことを指摘した。これは宇宙における粒子の熱的生成や相転移の可能性を議論する上で重要な結論である。 インフレーションの急激な加速膨張によってあらゆる数密度が薄められるため、インフレーション中のバリオン数は０となっている。そのため現実の宇宙を説明するためにはインフレーション後にバリオン数を作る必要があり、アフレック・ダイン機構はそのバリオン数を作る機構の一つとして知られている。本研究ではそのアフレック・ダイン機構によってインフレーション理論の予言に影響があることを指摘し、そのずれを定量的に与えた。これにより、近年の宇宙観測とはあまり整合性のないインフレーションモデルであっても、アフレック・ダイン機構の影響を考慮すると矛盾なく説明できる可能性があることが示された。また、アフレック・ダイン機構がインフレーション直後に働くという新しい可能性を指摘し、それがより一般の場合に働くことを示した。これにより、アフレック・ダイン機構においてバリオン数が生成されすぎてしまうという問題も解決することができた。

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Teaching Experience 7

  1. Special Topics in Physics I　Tohoku University

  2. Relativistic quantum mechanics　Tohoku University

  3. 物理学セミナー (3年生)　東北大学

  4. Invitation to Physical Science　Tohoku University

  5. Physics Seminar in English I　Tohoku University

  6. Exercises in mechanics II　Tohoku University

  7. ILASコロキウム 2021　東北大学教養教育院

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Media Coverage 4

  1. 宇宙背景放射の偏光面の回転を説明するアクシオンの運動機構の提唱 Myself

    東北大学 プレスリリース

    2021/10

    Type: Internet

  2. 暗黒物質はアクシオンか？ – ダークマター検出実験「XENON1T」と天体観測から検証する Myself

    academist Journal　研究コラム

    2020/12

    Type: Internet

  3. 「この人、研究中」ダークマターの真実 Myself

    NHK仙台ラジオ放送局　NHK ゴジだっちゃ!

    2020/11

    Type: TV or radio program

  4. ダークマターの正体はアクシオンか - XENON1T 実験の結果 を説明しダークマターと星の冷却異常をつなぐ説を提唱 - Myself

    東北大学 プレスリリース

    2020/10

    Type: Internet

Academic Activities 2

  1. Workshop on Cosmic Indicators of Dark Matter 2024

    2024/10/15 - 2024/10/17

    Activity type: Academic society, research group, etc.

  2. 基研研究会 素粒子物理学の進展２０２４

    2024/08/19 - 2024/08/23

    Activity type: Academic society, research group, etc.