Cosmology based on the most general single-field inflation model

• Project/Area Number: 24740161
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Rikkyo University
• Principal Investigator: Kobayashi Tsutomu 立教大学, 理学部, 准教授 (40580212)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Project Status: Completed (Fiscal Year 2015)
• Budget Amount: ¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000); Fiscal Year 2015: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2014: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2013: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2012: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
• Keywords: インフレーション / 修正重力 / 宇宙論 / 修正重力理論 / 初期宇宙 / 原始密度揺らぎ / 重力

Outline of Final Research Achievements

We have explored various aspects of gravitational theories beyond Einstein's General Relativity. We have focused on observational tests of such theories and gave a complete classification of cross-correlation functions of cosmological fluctuations. We have also addressed the stability of black holes in such theories.

Research Products

• [Journal Article] Removing Ostrogradski's ghost from cosmological perturbations in f(R,R_{mu nu}^2,C_{mu nu rho sigma}^2) gravity (2016)
  • Author(s): Yuji Akita, Tsutomu Kobayashi
  • Journal Title: MPLA Volume: 31 Issue: 11 Pages: 1650067-1650067
  • DOI: 10.1142/s021773231650067x
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Instability of hairy black holes in shift-symmetric Horndeski theories (2016)
  • Author(s): Hiromu Ogawa, Tsutomu Kobayashi, Teruaki Suyama
  • Journal Title: Physical Review D Volume: 93 Issue: 6 Pages: 1-9
  • DOI: 10.1103/physrevd.93.064078
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Universal instability of hairy black holes in Lovelock-Galileon theories in D dimensions (2016)
  • Author(s): Kazufumi Takahashi, Teruaki Suyama, Tsutomu Kobayashi
  • Journal Title: Physical Review D Volume: 93 Issue: 6 Pages: 1-9
  • DOI: 10.1103/physrevd.93.064068
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Primordial non-Gaussianities of gravitational waves beyond Horndeski theories (2016)
  • Author(s): Yuji Akita, Tsutomu Kobayashi
  • Journal Title: Phys.Rev. D Volume: D93 Issue: 4 Pages: 1-16
  • DOI: 10.1103/physrevd.93.043519
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Reheating and primordial gravitational waves in generalized Galilean genesis (2016)
  • Author(s): Sakine Nishi and Tsutomu Kobayashi
  • Journal Title: Journal of Cosmology and Astroparticle Physics Volume: 04 Issue: 04 Pages: 018-018
  • DOI: 10.1088/1475-7516/2016/04/018
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Galilean Creation of the Inflationary Universe (2015)
  • Author(s): T. Kobayashi, M. Yamaguchi, J. Yokoyama
  • Journal Title: JCAP Volume: 1507 Issue: 07 Pages: 1-22
  • DOI: 10.1088/1475-7516/2015/07/017
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] The most general second-order field equations of bi-scalar-tensor theory in four dimensions (2015)
  • Author(s): Seiju Ohashi,Tanahashi Norihiro, Tsutomu Kobayashi and Masahide Yamaguchi
  • Journal Title: JHEP Volume: 07 Issue: 7 Pages: 008-008
  • DOI: 10.1007/jhep07(2015)008
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Suppressing the primordial tensor amplitude without changing the scalar sector in quadratic curvature gravity (2015)
  • Author(s): Kohji Yajima, Tsutomu Kobayashi
  • Journal Title: Phys.Rev. D Volume: D92 Issue: 10 Pages: 1-7
  • DOI: 10.1103/physrevd.92.103503
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Breaking of Vainshtein screening in scalar-tensor theories beyond Horndeski (2015)
  • Author(s): Tsutomu Kobayashi, Yuki Watanabe, Daisuke Yamauchi
  • Journal Title: Physical Review D Volume: 91 Issue: 6 Pages: 064013-064013
  • DOI: 10.1103/physrevd.91.064013
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Generalized galilean genesis (2015)
  • Author(s): Sakine Nishi, Tsutomu Kobayashi
  • Journal Title: Journal of Cosmology and Astroparticle Physics Volume: 2015 Issue: 03 Pages: 1-18
  • DOI: 10.1088/1475-7516/2015/03/057
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Black hole perturbation in the most general scalar-tensor theory with second-order field equations. II. The even-parity sector (2014)
  • Author(s): Tsutomu Kobayashi, Hayato Motohashi, Teruaki Suyama
  • Journal Title: Physical Review D Volume: D89 Issue: 8 Pages: 1-12
  • DOI: 10.1103/physrevd.89.084042
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Exact black hole solutions in shift symmetric scalar-tensor theories (2014)
  • Author(s): Tsutomu Kobayashi, Norihiro Tanahashi
  • Journal Title: Progress of Theoretical and Experimental Physics Volume: 073E02 Issue: 7 Pages: 1-10
  • DOI: 10.1093/ptep/ptu096
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Covariant Stueckelberg analysis of de Rham-Gabadadze-Tolley massive gravity with a general fiducial metric (2014)
  • Author(s): Xian Gao, Tsutomu Kobayashi, Masahide Yamaguchi, Daisuke Yoshida
  • Journal Title: Physical Review D Volume: 90 Issue: 12 Pages: 124073-124073
  • DOI: 10.1103/physrevd.90.124073
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Cosmological matching conditions and galilean genesis in Horndeski's theory (2014)
  • Author(s): 西咲音、小林努、棚橋典大、山口昌英
  • Journal Title: Journal of Cosmology and Astroparticle Physics Volume: 03 Issue: 03 Pages: 8-8
  • DOI: 10.1088/1475-7516/2014/03/008
  • Peer Reviewed
• [Journal Article] Testing general scalar-tensor gravity and massive gravity with cluster lensing (2013)
  • Author(s): 成川達也、小林努、山内大介、齊藤遼
  • Journal Title: Physical Review D Volume: 87 Issue: 12 Pages: 1-10
  • DOI: 10.1103/physrevd.87.124006
  • Peer Reviewed
• [Journal Article] Multi-field G-inflation (2013)
  • Author(s): 小林努、棚橋典大、山口昌英
  • Journal Title: PHYSICAL REVIEW D Volume: 88 Issue: 8 Pages: 83504-83514
  • DOI: 10.1103/physrevd.88.083504
  • Peer Reviewed
• [Journal Article] Graceful exit from Higgs G-inflation (2013)
  • Author(s): K.Kamada, T.Kobayashi, T.Kunimitsu, M.Yamaguchi, J.Yokoyama
  • Journal Title: Physical Review D Volume: 88 Issue: 12 Pages: 1-12
  • DOI: 10.1103/physrevd.88.123518
  • Peer Reviewed
• [Journal Article] Full bispectra from primordial scalar and tensor perturbations in the most general single-field inflation model (2013)
  • Author(s): Xian Gao, Tsutomu Kobayashi, Maresuke Shiraishi, Masahide Yamaguchi, Jun'ichi Yokoyama, Shuichiro Yokoyama
  • Journal Title: Progress of Theoretical and Experimental Physics Volume: 未定
  • Peer Reviewed
• [Journal Article] Nonlinear superhorizon curvature perturbation in generic single-field inflation (2013)
  • Author(s): Yu-ichi Takamizu, Tsutomu Kobayashi
  • Journal Title: Progress of Theoretical and Experimental Physics Volume: 未定
  • Peer Reviewed
• [Journal Article] Black hole perturbation in the most general scalar-tensor theory with second-order field equations I: the odd-parity sector (2012)
  • Author(s): T. Kobayashi, H. Motohashi and T. Suyama
  • Journal Title: Physical Review D Volume: 85 Issue: 8 Pages: 1-8
  • DOI: 10.1103/physrevd.85.084025
  • Peer Reviewed
• [Journal Article] Generalized Higgs inflation (2012)
  • Author(s): Kohei Kamada, Tsutomu Kobayashi, Tomo Takahashi, Masahide Yamaguchi, Jun'ichi Yokoyama
  • Journal Title: Phys.Rev Volume: D86 Issue: 2 Pages: 23504-23504
  • DOI: 10.1103/physrevd.86.023504
  • Peer Reviewed
• [Journal Article] New Cosmological Solutions in Massive Gravity (2012)
  • Author(s): Tsutomu Kobayashi, Masaru Siino, Masahide Yamaguchi, Daisuke Yoshida
  • Journal Title: Physical Review D Volume: D86 Issue: 6
  • DOI: 10.1103/physrevd.86.061505
  • Peer Reviewed
• [Presentation] Galilean Creation of the Inflationary Universe (2015)
  • Author(s): Tsutomu Kobayashi
  • Organizer: Second LeCosPA International Symposium Everything About Gravity
  • Place of Presentation: 台北(台湾)
  • Year and Date: 2015-12-15
• [Presentation] Galilean Creation of the Inflationary Universe (2015)
  • Author(s): 小林努
  • Organizer: 日本物理学会秋季大会
  • Place of Presentation: 大阪市立大学(大阪府大阪市)
  • Year and Date: 2015-09-27
• [Presentation] Galilean Creation of the Inflationary Universe (2015)
  • Author(s): Tsutomu Kobayashi
  • Organizer: MG14
  • Place of Presentation: ローマ(イタリア)
  • Year and Date: 2015-07-14
• [Presentation] Breaking of Vainshtein screening in scalar-tensor theories beyond Horndeski (2015)
  • Author(s): 小林努
  • Organizer: 日本物理学会年次大会
  • Place of Presentation: 早稲田大学（東京都新宿区）
  • Year and Date: 2015-03-21
  • Invited
• [Presentation] Generalized Galilean Genesis (2014)
  • Author(s): Tsutomu Kobayashi
  • Organizer: CosPA 2014
  • Place of Presentation: オークランド（ニュージーランド）
  • Year and Date: 2014-12-09
• [Presentation] Exact black hole solutions in shift symmetric scalar-tensor theories (2014)
  • Author(s): 小林努
  • Organizer: 日本物理学会秋季大会
  • Place of Presentation: 佐賀大学（佐賀県佐賀市）
  • Year and Date: 2014-09-20
• [Presentation] Vainshtein mechanism in the Horndeski theory and beyond (2014)
  • Author(s): Tsutomu Kobayashi
  • Organizer: Relativistic Cosmology
  • Place of Presentation: 京都大学基礎物理学研究所（京都府京都市）
  • Year and Date: 2014-09-09
  • Invited
• [Presentation] 一般相対論の拡張 (2014)
  • Author(s): 小林努
  • Organizer: 背景放射で拓く宇宙創成の物理 ～ インフレーションからダークエイジまで ～ シンポジウム 2014
  • Place of Presentation: 理研和光キャンパス（埼玉県和光市）
  • Year and Date: 2014-06-03
  • Invited
• [Presentation] Full bispectra from primordial scalar and tensor perturbations in the most general single-field inflation model (2013)
  • Author(s): 小林努
  • Organizer: 日本物理学会年次大会
  • Place of Presentation: 広島大学
• [Presentation] Generalized Higgs inflation (2012)
  • Author(s): 小林努
  • Organizer: 日本物理学会秋季大会
  • Place of Presentation: 京都産業大学
• [Presentation] Vainshtein mechanism in Horndeski’s general scalar-tensor theory (and in massive gravity)
  • Author(s): Tsutomu Kobayashi
  • Organizer: Mini-workshop "Massive gravity and its cosmological implications"
  • Place of Presentation: カブリ数物連携宇宙研究機構（Kavli IPUM）
  • Invited
• [Presentation] Cosmology of Generalized Galileons
  • Author(s): Tsutomu Kobayashi
  • Organizer: GR20/Amaldi10
  • Place of Presentation: ワルシャワ大学（ポーランド）
• [Presentation] Horndeski’s theory: a unified description of modified gravity
  • Author(s): Tsutomu Kobayashi
  • Organizer: JGRG23
  • Place of Presentation: 弘前大学
  • Invited
• [Presentation] Multi-field G-inflation
  • Author(s): 小林努
  • Organizer: 日本物理学会秋季大会
  • Place of Presentation: 高知大学
• [Presentation] The most general second-order scalar-tensor theory
  • Author(s): 小林努
  • Organizer: 第2回観測的宇宙論ワークショップ
  • Place of Presentation: 国立天文台
  • Invited
• [Presentation] Vainshtein mechanism in the most general scalar-tensor theory
  • Author(s): 小林努
  • Organizer: Nonlinear massive gravity theory and its observational test
  • Place of Presentation: 京都大学基礎物理学研究所