Noncanonical scalar fields and the primeval thermal bath

Abstract

In this paper, we show that a smooth dynamic evolution from an initial unstable de Sitter stage to the standard radiation phase can analytically be described by a dominant noncanonical scalar field. For all practical purposes, at the end of the vacuum decaying process, the remaining potential energy density is completely stored in the kinetic part of the field satisfying the radiation equation of state. In this model, the early universe is nonsingular, free of horizon and different from many inflationary variants none post-inflationary reheating is required since the formation of the thermal bath is concomitant with inflation. The thermodynamic evolution of the thermal bath is determined. It is also shown that the resulting noncanonical cosmology can be rigorously interpreted as a dynamical [Formula: see text]-model (vacuum fluid) whose spontaneous decaying process into radiation may be the origin of the primeval thermal bath.