Matter-antimatter asymmetry creation in the early Universe and particle collective excitations

• Project/Area Number: 15K17644
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Nagoya University
• Principal Investigator: Miura Kohtaroh 名古屋大学, 基礎理論研究センター, 研究員 (50511432)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Project Status: Completed (Fiscal Year 2017)
• Budget Amount: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2016: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2015: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
• Keywords: ニュートリノ集団励起とレプトン数生成 / 物質-反物質非対称性 / 素粒子論的宇宙論 / 電弱相転移と素粒子集団励起 / Leptogenesis / 素粒子(lepton)の集団励起 / 高温初期宇宙 / 有限温度ゲージ理論 / 宇宙の物質-反物質非対称性 / 電弱-TeVスケ－ル宇宙 / Resonant Leptogenesis / 右巻きニュートリノ崩壊率 / 有限温度 / 発散回避メカニズム / 非自明なスペクトル関数

Outline of Final Research Achievements

We have investigated a creation mechanism of matter-antimatter asymmetry observed in the Universe in terms of a collective excitation of elementary particles in the electroweak phase transition (EWPT) era. We have focused on the resonant-leptogenesis in which the lepton number would be created at around the EWPT - a frontier of the high energy particle physics, and it is thus under scrutiny with phenomenological interests. An important feature in the EWPT is that left-handed neutrinos possess a non-trivial collective excitation due to the presence of massive weak bosons. We have taken account of this effect and evaluated the decay rate of the right-handed neutrino, a key quantity in the leptogenesis. Comparing to the case assuming massless weak bosons, the decay rate gets 30% enhancement at around 100 GeV.

Research Products

• [Journal Article] Flavor-singlet spectrum in multi-flavor QCD (2018)
  • Author(s): Aoki Yasumichi、Aoyama Tatsumi、Bennett Ed、Kurachi Masafumi、Maskawa Toshihide、Miura Kohtaroh、Nagai Kei-ichi、Ohki Hiroshi、Rinaldi Enrico、Shibata Akihiro、Yamawaki Koichi、Yamazaki Takeshi
  • Journal Title: EPJ Web Conferences Volume: 175 Pages: 08023-08023
  • DOI: 10.1051/epjconf/201817508023
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Light flavor-singlet scalars and walking signals in Nf=8 QCD on the lattice (2017)
  • Author(s): Aoki Yasumichi、Aoyama Tatsumi、Bennett Ed、Kurachi Masafumi、Maskawa Toshihide、Miura Kohtaroh、Nagai Kei-ichi、Ohki Hiroshi、Rinaldi Enrico、Shibata Akihiro、Yamawaki Koichi、Yamazaki Takeshi、LatKMI Collaboration
  • Journal Title: Physical Review D Volume: 96 Pages: 014508-014508
  • DOI: 10.1103/physrevd.96.014508
  • Peer Reviewed / Int'l Joint Research
• [Presentation] Decay Rate of Right-Handed Neutrinos in Light of Collective Excitations at Electroweak Scale (2016)
  • Author(s): 三浦光太郎
  • Organizer: Strong and Electroweak Matter 2016
  • Place of Presentation: University of Stavanger, Norway
  • Year and Date: 2016-07-11
  • Int'l Joint Research