Broken Phase Sphaleron and Baryogenesis
|講演者||Wen Yin 氏（東北大学 特任助教）|
|会場||ハイブリッド形式 : オンライン (Zoom) + セミナールーム（研究本館321,322)|
We will explore baryogenesis scenarios in which the Universe is reheated to temperatures below 100 GeV. Such low temperatures may result from the decay of long-lived massive particles, which are found in various beyond Standard Model scenarios, or from a strongly first-order electroweak phase transition. Even if the reheating temperature is relatively low, the scattering of energetic particles in these scenarios can produce center-of-mass energies higher than the typical sphaleron mass. Optimistic estimates suggest that successful baryogenesis may be achievable for reheating temperatures as low as 0.1-1 GeV, provided that the sphaleron cross section is enhanced at high energies. Furthermore, a simple extension of the Standard Model can lead to sufficient baryon production by enhancing the W-boson coupling, even if more pessimistic estimates for the sphaleron rate are accurate. In both cases, collider and cosmic-ray experiments can probe the same process responsible for baryogenesis if the 2-to-many sphaleron reaction is significant enough.