2021-04-26

UTAPwiki/セミナー/初期宇宙・相対論速報

Title: Electroweak-like Baryogenesis with New Chiral Matter †

Speaker: Kohei Fujikura †

Abstract:
We propose a framework where a phase transition associated with a gauge symmetry breaking that occurs (not far) above the electroweak scale sets a stage for baryogenesis similar to the electroweak baryogenesis in the Standard Model. New chiral fermions charged under the extended gauge symmetry have nonzero lepton numbers, which makes the B-L symmetry anomalous. The new lepton sector contains a large flavor-dependent CP violation, similar to the Cabibbo-Kobayashi-Maskawa phase, without inducing sizable electric dipole moments of the Standard Model particles. A bubble wall dynamics associated with the first-order phase transition and sphaleron processes generate a lepton asymmetry, which is transferred into a baryon asymmetry via the ordinary electroweak sphaleron process. Unlike the Standard Model electroweak baryogenesis, the new phase transition can be of the strong first order and the new CP violation is not significantly suppressed by Yukawa couplings, so that the observed asymmetry can be produced. The model can be probed by collider searches for new particles and the observation of gravitational waves. This seminar is based on ref. [4].

References:
[1] G.R. Farrar and M.E. Shaposhnikov, “Baryon asymmetry of the universe in the minimal standard model" [hep-ph/9305275]
[2] M.B. Gavela, P.Hernandez, J. Orloff and O. Pene, “Standard Model CP violation and baryon asymmetry” [hep-ph/9312215]
[3] P. Huet and E. Sather, “Electroweak baryogenesis and standard model CP violation" [hep-ph/9404302]
[4] K. Fujikura, K. Harigaya, Y. Nakai and R. Wang “Electroweak-like Baryogenesis with New Chiral Matter” [arXiv:2103.05005]