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Research on singularity problem in early universe

Research Project

Project/Area Number 19J00294
Research Category

Grant-in-Aid for JSPS Fellows

Allocation TypeSingle-year Grants
Section国内
Review Section Basic Section 15010:Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics
Research InstitutionKobe University

Principal Investigator

吉田 大介  神戸大学, 理学研究科, 特別研究員(PD) (90849861)

Project Period (FY) 2019-04-25 – 2022-03-31
Project Status Completed (Fiscal Year 2021)
Budget Amount *help
¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2021: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2020: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Keywords時空特異点 / 宇宙論 / 一般相対論 / 重力理論 / 初期宇宙論 / 特異点 / 初期宇宙
Outline of Research at the Start

時空特異点の回避は、超高エネルギー領域における未知の量子重力理論に期待する性質の一つです。しかしながら、そのような性質を反映した有効的な古典重力理論は未だ確立していません。本研究では超高エネルギー領域の重力理論の理解のため、これまで注目されていなかった非スカラー曲率特異点をも含む、あらゆる時空特異点の生じない有効古典重力理論の構築とその安定化をおこないます。さらに、上記の問題を解決した理論においてインフレーション宇宙論に応用し、密度ゆらぎの観測による、特異点解消の検証方法の提唱をおこないます。

Outline of Annual Research Achievements

本研究の目的は、超高エネルギー領域の重力理論の理解のため、宇宙初期特異点の性質を解明し、あらゆる特異点を防ぐための機構を明らかにすることです。
これまでの研究において、「スカラー曲率特異点」と呼ばれる種類の特異点については、その生成を緩和するモデルが提唱できています。一方で、これとは異なる種類の「非スカラー曲率特異点」と呼ばれる特異点については、その性質が、最も単純な宇宙である一様等方宇宙の場合にしか明らかではありませんでした。本年度は、これまで一様等方宇宙に対して行っていた解析を、一様等方とは限らないより一般の宇宙へと拡張しました。その結果、一様等方でないような宇宙において「非スカラー曲率特異点」に分類される宇宙初期特異点が存在するかどうかの判別法を明らかにしました。
特に、この判別法により、前年度までの研究で得られていた、安定でかつスカラー曲率特異点を持たないような宇宙が、実は、非スカラー曲率特異点を持つということが明らかになりました。したがって、この結果はこれまでの枠組みがあらゆる特異点を解消する機構としては不十分であるを表しており、さらなる研究が必要であることが明らかになりました。

Research Progress Status

令和3年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和3年度が最終年度であるため、記入しない。

Report

(3 results)
  • 2021 Annual Research Report
  • 2020 Annual Research Report
  • 2019 Annual Research Report
  • Research Products

    (26 results)

All 2022 2021 2020 2019 Other

All Int'l Joint Research (3 results) Journal Article (10 results) (of which Int'l Joint Research: 3 results,  Peer Reviewed: 10 results,  Open Access: 3 results) Presentation (13 results) (of which Int'l Joint Research: 8 results,  Invited: 5 results)

  • [Int'l Joint Research] Sun Yat-sen University(中国)

    • Related Report
      2020 Annual Research Report
  • [Int'l Joint Research] Max Planck Institute(ドイツ)

    • Related Report
      2020 Annual Research Report
  • [Int'l Joint Research] Max Planck Institute(ドイツ)

    • Related Report
      2019 Annual Research Report
  • [Journal Article] Quasinormal modes of charged black holes with corrections from nonlinear electrodynamics2022

    • Author(s)
      Nomura Kimihiro、Yoshida Daisuke
    • Journal Title

      Physical Review D

      Volume: 105 Issue: 4 Pages: 044006-044006

    • DOI

      10.1103/physrevd.105.044006

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Past extendibility and initial singularity in Friedmann-Lema?tre-Robertson-Walker and Bianchi I spacetimes2021

    • Author(s)
      Nomura Kimihiro、Yoshida Daisuke
    • Journal Title

      Journal of Cosmology and Astroparticle Physics

      Volume: 2021 Issue: 07 Pages: 047-047

    • DOI

      10.1088/1475-7516/2021/07/047

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed
  • [Journal Article] String excitation by initial singularity of inflation2021

    • Author(s)
      Nishii Kanji、Yoshida Daisuke
    • Journal Title

      Journal of High Energy Physics

      Volume: 2021 Issue: 10

    • DOI

      10.1007/jhep10(2021)025

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed
  • [Journal Article] O(d,d;Z) invariant Fierz-Pauli massive gravity2021

    • Author(s)
      Noumi Toshifumi、Saito Kaishu、Soda Jiro、Yoshida Daisuke
    • Journal Title

      Physical Review D

      Volume: 103 Issue: 4 Pages: 1-8

    • DOI

      10.1103/physrevd.103.046011

    • NAID

      120006993638

    • Related Report
      2020 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Stability of magnetic black holes in general nonlinear electrodynamics2020

    • Author(s)
      Nomura Kimihiro、Yoshida Daisuke、Soda Jiro
    • Journal Title

      Physical Review D

      Volume: 101 Issue: 12 Pages: 1-21

    • DOI

      10.1103/physrevd.101.124026

    • NAID

      120006894041

    • Related Report
      2020 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Theories with limited extrinsic curvature and a nonsingular anisotropic universe2020

    • Author(s)
      Sakakihara Yuki、Yoshida Daisuke、Takahashi Kazufumi、Quintin Jerome
    • Journal Title

      Physical Review D

      Volume: 102 Issue: 8 Pages: 1-16

    • DOI

      10.1103/physrevd.102.084004

    • NAID

      120006938926

    • Related Report
      2020 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Ghost-free resummation of gravitational interactions of a two-form gauge field2020

    • Author(s)
      Takahashi Kazufumi、Yoshida Daisuke
    • Journal Title

      Physical Review D

      Volume: 101 Issue: 2

    • DOI

      10.1103/physrevd.101.024049

    • NAID

      120006796522

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Cuscuton gravity as a classically stable limiting curvature theory2020

    • Author(s)
      Quintin Jerome、Yoshida Daisuke
    • Journal Title

      Journal of Cosmology and Astroparticle Physics

      Volume: 2020 Issue: 02 Pages: 016-016

    • DOI

      10.1088/1475-7516/2020/02/016

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Two-form gauge theory dual to scalar-tensor theory2019

    • Author(s)
      Yoshida Daisuke
    • Journal Title

      Physical Review D

      Volume: 100 Issue: 8

    • DOI

      10.1103/physrevd.100.084047

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Birth of de Sitter universe from a time crystal universe2019

    • Author(s)
      Yoshida Daisuke、Soda Jiro
    • Journal Title

      Physical Review D

      Volume: 100 Issue: 12 Pages: 123531-123531

    • DOI

      10.1103/physrevd.100.123531

    • NAID

      120006796517

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed / Open Access
  • [Presentation] Spacetime singularity in accelerated universe2022

    • Author(s)
      Daisuke Yoshida
    • Organizer
      Kagoshima Workshop on Quantum Aspects of Gravitation
    • Related Report
      2021 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Classification of initial singularity2022

    • Author(s)
      Daisuke Yoshida
    • Organizer
      Dawn of Gravitational-wave Cosmology and Theory of Gravity
    • Related Report
      2021 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] 量子補正を加えた光の軌道に基づく時空の因果構造2021

    • Author(s)
      吉田大介
    • Organizer
      京阪神ブラックホール研究会
    • Related Report
      2021 Annual Research Report
    • Invited
  • [Presentation] Singularity theorem for non-singular universe2021

    • Author(s)
      Daisuke Yoshida
    • Organizer
      JGRG30
    • Related Report
      2021 Annual Research Report
    • Int'l Joint Research
  • [Presentation] インフレーション宇宙と特異点2021

    • Author(s)
      吉田大介
    • Organizer
      第22回特異点研究会
    • Related Report
      2021 Annual Research Report
  • [Presentation] T双対性を持ったmassive gravity2021

    • Author(s)
      吉田大介
    • Organizer
      日本物理学会第76回年次大会(2021)
    • Related Report
      2020 Annual Research Report
  • [Presentation] Classification of initial singulairty2020

    • Author(s)
      吉田大介
    • Organizer
      online JGRG workshop 2020
    • Related Report
      2020 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Stability of Charged Black Holes in Nonlinear Electrodynamics2020

    • Author(s)
      吉田大介
    • Organizer
      4th Korea-Japan bilateral workshop on string axion cosmology
    • Related Report
      2019 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Birth of de Sitter Universe from a time crystal Universe2020

    • Author(s)
      吉田大介
    • Organizer
      日本物理学会第75回年次大会
    • Related Report
      2019 Annual Research Report
  • [Presentation] インフレーション宇宙における初期特異点2019

    • Author(s)
      吉田大介
    • Organizer
      日本物理学会2019年秋季大会
    • Related Report
      2019 Annual Research Report
  • [Presentation] Singularities in inflationary Universes2019

    • Author(s)
      吉田大介
    • Organizer
      Potor-6
    • Related Report
      2019 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Electromagnetic duality for scalar-tensor theory2019

    • Author(s)
      吉田大介
    • Organizer
      3rd Korea-Japan bilateral workshop on string axion cosmology
    • Related Report
      2019 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Birth of de Sitter Universe from time crystal2019

    • Author(s)
      吉田大介
    • Organizer
      JGRG29,
    • Related Report
      2019 Annual Research Report
    • Int'l Joint Research

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Published: 2019-05-29   Modified: 2024-03-26  

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