[tw-hepnet] NCTS Seminar - Particle Physics Journal Club 2025/06/02 (Mon.) 12:30
0 views
Skip to first unread message
Yu-Rou Tsang
May 27, 2025, 9:01:11 PMMay 27
to tw-h...@googlegroups.com
***NCTS Seminar***
Particle Physics Journal Club
===================================================
Speaker: Prof. Hsiang-nan Li (AS)
Talk title: Realization of electroweak baryogenesis by fourth generation fermions
Time: 2025/06/02 (Mon.) 12:30
Place: NCTS Physics 4F Lecture Hall, Cosmology Hall, NTU
Abstract:
We demonstrate that the electroweak baryogenesis can be realized in the extended Standard Model with sequential fourth generation fermions (SM4).
The solution to the coupled Dyson-Schwinger equations for the fermion and Higgs masses indicates that fourth generation quarks t′ and b′ with the Yukawa couplings above the threshold g^c_Q ~ 9.1 form condensates.
This critical coupling, greater than the value g^f_Y ~ 7 at the ultraviolet fixed point of the renormalization-group evolution in the SM4, implies the existence of an electroweak symmetric phase at a high energy. The t′ and b′ Yukawa couplings evolve as the energy decreases, and exceed g^c_Q at a lower scale. The Higgs potential with the dynamical symmetry breaking effect from heavy quark condensates, the one-loop correction from the heavy scalars formed by t′ and b′ quarks and the temperature-dependent contribution from fourth generation leptons allow the first-order phase transition characterized by the ratio phi_c/T_c ~ 0.9, where phi_c is the location of the Higgs potential minimum at the critical temperature T_c. Together with the baryon number violating sphaleron interaction inherent in the Standard Model and the enhanced CP violation source from fourth generation quarks, the baryon asymmetry in the Universe can be achieved.
This critical coupling, greater than the value g^f_Y ~ 7 at the ultraviolet fixed point of the renormalization-group evolution in the SM4, implies the existence of an electroweak symmetric phase at a high energy. The t′ and b′ Yukawa couplings evolve as the energy decreases, and exceed g^c_Q at a lower scale. The Higgs potential with the dynamical symmetry breaking effect from heavy quark condensates, the one-loop correction from the heavy scalars formed by t′ and b′ quarks and the temperature-dependent contribution from fourth generation leptons allow the first-order phase transition characterized by the ratio phi_c/T_c ~ 0.9, where phi_c is the location of the Higgs potential minimum at the critical temperature T_c. Together with the baryon number violating sphaleron interaction inherent in the Standard Model and the enhanced CP violation source from fourth generation quarks, the baryon asymmetry in the Universe can be achieved.
--
Yu-Rou Tsang 臧雨柔Administrative Staff
Physics Division, National Center for Theoretical Sciences (NCTS), Taipei 10617, Taiwan
Tel: +886-2-3366-9932
Reply all
Reply to author
Forward
0 new messages