Yamamoto, Naoki

写真a

Affiliation

Faculty of Science and Technology, Department of Physics (Yagami)

Position

Associate Professor

Related Websites

Career 【 Display / hide

  • 2007.04
    -
    2010.03

    東京大学, 大学院理学系研究科, 日本学術振興会 特別研究員 (DC1)

  • 2010.04
    -
    2012.03

    University of Washington, Institute for Nuclear Theory, JSPS Postdoctoral Fellow for Research Abroad / Research Associate

  • 2012.04
    -
    2013.08

    京都大学, 基礎物理学研究所, 日本学術振興会 特別研究員 (PD)

  • 2013.09
    -
    2014.03

    University of Maryland, Maryland Center for Fundamental Physics, Research Associate

  • 2014.04
    -
    2017.03

    慶應義塾大学, 理工学部物理学科, 専任講師

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Academic Background 【 Display / hide

  • 2001.04
    -
    2005.03

    The University of Tokyo, 理学部, Department of Physics

    University, Graduated

  • 2005.04
    -
    2007.03

    The University of Tokyo, Faculty of Science, Department of Physics

    Graduate School, Completed, Master's course

  • 2007.04
    -
    2010.03

    The University of Tokyo, Faculty of Science, Department of Physics

    Graduate School, Completed, Doctoral course

Academic Degrees 【 Display / hide

  • 博士(理学), The University of Tokyo, Coursework, 2010.03

 

Research Areas 【 Display / hide

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

 

Papers 【 Display / hide

  • Unstable Nambu-Goldstone modes

    Naoki Yamamoto, Ryo Yokokura

    Physical Review D 106   105004(1-9) 2022.11

    Research paper (scientific journal), Joint Work, Accepted

  • Chiral gravitational waves from thermalized neutrinos in the early Universe

    Philipp Gubler, Naoki Yamamoto, Di-Lun Yang

    Journal of Cosmology and Astroparticle Physics 09 ( 025 ) 1 - 36 2022.09

    Research paper (scientific journal), Joint Work, Accepted

     View Summary

    We investigate polarized gravitational waves generated by chiral fermions in the early Universe. In particular, we focus on the contribution from left-handed neutrinos in thermal equilibrium with finite temperature and chemical potential in the radiation dominated era. We compute the correlation functions of gravitational fields pertinent to the Stokes parameter V characterizing the circular polarization of gravitational waves in the Minkowski and expanding spacetime backgrounds. In the expanding universe, we find that the thermalized neutrinos induce a non-vanishing V linear to the neutrino degeneracy parameter and wavenumber of gravitational waves in the long wavelength region. While the magnitude of the gravitational waves generated by thermal neutrinos is too small to be detectable by current and planned third generation gravitational wave detectors, their observations by future generation detectors for ultra-high frequency regimes could provide information on the neutrino degeneracy parameter in the early Universe.

  • Chiral plasma instability and inverse cascade from nonequilibrium left-handed neutrinos in core-collapse supernovae

    Jin Matsumoto, Naoki Yamamoto, Di-Lun Yang

    Physical Review D 105 ( 12 ) 123029(1-7) 2022.06

    Research paper (scientific journal), Joint Work, Accepted,  ISSN  24700010

     View Summary

    We show that the backreaction of left-handed neutrinos out of equilibrium on the matter sector induces an electric current proportional to a magnetic field even without a chiral imbalance for electrons in core-collapse supernovae. We derive the transport coefficient of this effect based on the recently formulated chiral radiation transport theory for neutrinos. This chiral electric current generates a strong magnetic field via the so-called chiral plasma instability, which could provide a new mechanism for the strong and stable magnetic field of magnetars. We also numerically study the physical origin of the inverse cascade of the magnetic energy in the magnetohydrodynamics including this current. Our results indicate that incorporating the chiral effects of neutrinos would drastically modify the hydrodynamic evolutions of supernovae, which may also be relevant to the explosion dynamics.

  • Photonic spin Hall effect from quantum kinetic theory in curved spacetime

    Kazuya Mameda, Naoki Yamamoto, Di-Lun Yang

    Physical Review D 105   096019(1-9) 2022.05

    Research paper (scientific journal), Joint Work, Accepted

  • Magnetic field induced neutrino chiral transport near equilibrium

    Naoki Yamamoto, Di-Lun Yang

    Physical Review D 104 ( 12 ) 123019(1-15) 2021.12

    Research paper (scientific journal), Joint Work, Accepted,  ISSN  24700010

     View Summary

    Based on the recently formulated chiral radiation transport theory for left-handed neutrinos, we study the chiral transport of neutrinos near thermal equilibrium in core-collapse supernovae. We first compute the near-equilibrium solution of the chiral radiation transport equation under the relaxation time approximation, where the relaxation time is directly derived from the effective field theory of the weak interaction. By using such a solution, we systematically derive analytic expressions for the nonequilibrium corrections of the neutrino energy-momentum tensor and neutrino number current induced by magnetic fields via the neutrino absorption on nucleons. In particular, we find the nonequilibrium neutrino energy current proportional to the magnetic field. We also discuss its phenomenological consequences such as the possible relation to pulsar kicks.

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Papers, etc., Registered in KOARA 【 Display / hide

Reviews, Commentaries, etc. 【 Display / hide

  • カイラリティと宇宙

    山本 直希

    数理科学(特集:カイラリティとは何か) 59 ( 3 ) 45 - 51 2021.03

    Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media), Single Work

  • トポロジカル輸送現象入門

    山本 直希

    原子核研究 64   22 - 29 2020.02

    Article, review, commentary, editorial, etc. (scientific journal)

  • Chiral Transport Phenomena

    山本 直希

    原子核研究 63 ( 2 ) 72 - 73 2019.03

    Article, review, commentary, editorial, etc. (scientific journal), Single Work

  • 相対論的流体力学

    山本 直希

    数理科学(特集:相対論的思考法のすすめ) 55 ( 8 ) 36 - 42 2017.08

    Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media), Single Work

Presentations 【 Display / hide

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Research Projects of Competitive Funds, etc. 【 Display / hide

  • 素粒子論に基づく超新星のカイラル輻射流体力学の構築

    2019.04
    -
    2022.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Principal investigator

  • カイラル輸送現象による超新星爆発・初期宇宙の新物理

    2016.04
    -
    2019.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Young Scientists (B), Principal investigator

Works 【 Display / hide

  • 他大学セミナー招待講演(東京工業大学 宇宙論研究室)

    山本 直希

    東京工業大学, 

    2022.07

    Other

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    Gravitational Spin Hall Effect

  • 他研究所セミナー招待講演(高エネルギー加速器研究機構)

    山本 直希

    オンライン, 

    2020.07

    Other

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    Magnetic monopoles and fermion number violation in chiral matter

  • 他研究所セミナー招待講演(高エネルギー加速器研究機構)

    山本 直希

    高エネルギー加速器研究機構, 

    2019.06

    Other

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    Chiral Soliton Lattice in QCD

  • 他大学セミナー招待講演(早稲田大学 天体物理学研究室)

    早稲田大学 天体物理学研究室, 

    2018.07

    Other

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    Chirality and Astrophysics

  • 他大学セミナー招待講演(東京大学 駒場キャンパス 素粒子論研究室)

    東京大学 駒場キャンパス 素粒子論研究室, 

    2017.12

    Other

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    カイラル輸送現象:ニュートリノから超新星爆発へ

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Awards 【 Display / hide

  • 第28回 井上研究奨励賞

    2012.02, 井上科学振興財団

    Type of Award: Award from publisher, newspaper, foundation, etc.

  • 2009年度 東京大学 大学院理学系研究科 研究奨励賞(博士)

    2010.03, 東京大学 大学院理学系研究科

    Type of Award: Other

 

Courses Taught 【 Display / hide

  • QUANTUM MECHANICS 3

    2022

  • NUCLEAR PHYSICS

    2022

  • LITERATURE OF PHYSICS

    2022

  • LIBERAL ARTS AND SCIENCES SEMINAR 2

    2022

  • INDEPENDENT STUDY ON FUNDAMENTAL SCIENCE AND TECHNOLOGY

    2022

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Memberships in Academic Societies 【 Display / hide

  • 日本物理学会, 

    2006.09
    -
    Present