5/22 12:30 Prof. Hsiang-Nan Li (AS IoP)Realization of electroweak baryogenesis by fourth generation fermions(R521, 5F, General Building II, Nat'l Tsing Hua Univ.)
******** CTCD/NTHU HEP Seminar ********
Speaker ：Prof. Hsiang-Nan Li (AS IoP)
Title ：Realization of electroweak baryogenesis by fourth generation
fermions
Time ：12:30-13:30, Thursday, 2025/5/22
Place ：R521, 5F, General Building II, Nat'l Tsing Hua Univ.
Host ： Prof. Po-Yen Tseng (NTHU)
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.
Speaker ：Prof. Hsiang-Nan Li (AS IoP)
Title ：Realization of electroweak baryogenesis by fourth generation
fermions
Time ：12:30-13:30, Thursday, 2025/5/22
Place ：R521, 5F, General Building II, Nat'l Tsing Hua Univ.
Host ： Prof. Po-Yen Tseng (NTHU)
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.