Event details
Speaker: Wen-Yuan Ai
Institute: Kings College London
Title: Fate of $Z_2$ symmetric scalar condensates in the early Universe
Abstract:
Scalar condensates are common objects in cosmology, existing in
various forms (strings, domain walls, oscillating condensates). In this
talk, I will discuss the evolution of $Z_2$ symmetric, oscillating
homogeneous scalar condensates in the early Universe from first
principles (non-equilibrium quantum field theory). We show that the
decay of such scalar condensates cannot be complete because their decay
rates always decrease faster than the Hubble parameter at sufficiently
late times. This is due to either the amplitude dependence or the
temperature dependence in the condensate decay rates. This incomplete
decay of $Z_2$ scalar condensates is reminiscent of the freeze-out
process of ordinary particles. Consequently, such oscillating scalar
condensates make an irreducible contribution to the dark matter relic
abundance unless they fragment.