Hubble-induced phase transitions: Walls are not forever

TL;DR

This paper investigates how non-minimally coupled scalar fields during a kinetic-dominated era after inflation can lead to transient domain walls, which typically vanish before nucleosynthesis, with implications for early universe phenomenology.

Contribution

It provides a detailed analytical study of the dynamics of spectator fields and the formation and evolution of domain walls in quintessential inflation scenarios with non-minimal coupling.

Findings

Domain walls form due to symmetry breaking after inflation.

Most domain walls decay before big bang nucleosynthesis.

The lifetime of walls depends on inflation scale, coupling, and self-interactions.

Abstract

The interplay between non-minimally coupled scalar fields and a kinetic-dominated era following the end of inflation triggers the spontaneous symmetry breaking of internal symmetries and the subsequent evolution of the fields towards large expectation values. We present here a detailed analysis of the associated dynamics in quintessential inflation scenarios involving a non-minimally coupled $Z_2$-symmetric spectator field. By analytically following the evolution of the spectator field fluctuations at early times, we characterize the formation of classical, homogeneous and spatially-localized field configurations separated by domain walls. The life expectancy of these dividing barriers is set by the scale of inflation, the non-minimal coupling and self-interactions of the spectator field and potentially, but not necessarily, the duration of the heating stage. For most of the parameter space, the domain walls are doomed to disappear before big bang nucleosynthesis. Potential phenomenological consequences of the scenario are discussed.