  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 non-interacting scalar field at the time phase transition
happens. The upper bound 860 GeV of the cutoff scale in the conventional case
can be improved to 1 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 non-interacting scalar field at the
electroweak scale can then make this model satisfy the sphaleron bound with a
certain parameter space.

High Energy Physics - Phenomenology