Sphaleron bound in some nonstandard cosmology scenarios

Abstract

In the first scenario, we revise the upper bound of the cutoff scale of the dimension-six potential Higgs operator required for a successful electroweak baryogenesis in the case of a modified expansion history caused by the existence of a noninteracting scalar field at the time phase transition happens. The upper bound 860[Formula: see text]GeV of the cutoff scale in the conventional case can be improved to 1[Formula: see text]TeV in the modified expansion case under certain conditions. In the second scenario, we consider the Randall–Sundrum type II model. We show that the lower bound of the five-dimensional Planck scale in this model, which is determined from the validity of Newtonian gravitational potential at small distance, turns out to be crucial in eliminating this model as a viable candidate to satisfy the sphaleron bound; however, again modifying the expansion history by including a noninteracting scalar field at the electroweak scale can then make this model satisfy the sphaleron bound with a certain parameter space.

Asymmetric Dark Matter in Baryon Asymmetrical Universe

“…These parameters obviously depend on the local characteristics and global behavior of the scalar potential, i.e., on the type and energetic scale of the SM extension. Thus, various modifications of the SM Higgs sector (taking into account triple Higgs interactions or additional Higgs doublets, the emergence of a new scalar field between the epochs of inflation and radiation [29]) or the transition to other scales (from the SM fermions to the forth generation of heavy quarks or to techniquarks and composite scalars) are considered as possible scenarios providing EW baryogenesis due to enhancing sphaleron transitions.…”

Shaft inflation in Randall-Sundrum model

“…There can also exist an upper bound if one wants to use the model to address other problems such as baryogenesis[23] but we will not consider it here.…”