Particle Dark Matter Density and Entropy Production in the Early Universe

Dark Matter (DM) density is reduced if entropy production takes place after DM particles abundance frozen out in the early universe. We study a possibility of such reduction due to electroweak phase transition (EWPT). compare scenarios standard model (SM) and its simplest extension, two-Higgs doublet (2HDM). Assuming EWPT second order SM scenario first 2HDM, we calculate release these corresponding dilution preexisting find effect significant for confrontation with observations any form possible (including primordial black holes (PBHs)), which out, decoupled, in, or formed before EWPT.