Warm inflation in a Universe with a Weylian boundary

TL;DR

This paper explores how boundary terms described by Weylian geometry influence warm inflation, revealing that Weyl vectors significantly affect early Universe radiation creation and the transition from inflation to deceleration.

Contribution

It introduces a generalized framework for warm inflation incorporating Weylian boundary effects, extending Einstein-Hilbert action and deriving new cosmological equations.

Findings

Radiation is generated during early Universe expansion.

Weyl vector significantly impacts radiation creation.

Transition from inflation to deceleration is influenced by boundary effects.

Abstract

We investigate the influence of boundary terms in the warm inflationary scenario, by considering that in the Einstein-Hilbert action the boundary can be described in terms of a Weyl-type geometry. The gravitational action, as well as the field equations, are thus extended to include new geometrical terms, coming from the non-metric nature of the boundary, and depending on the Weyl vector, and its covariant derivatives. We investigate the effects of these new boundary terms by considering the warm inflationary scenario of the early evolution of the Universe, in the presence of a scalar field. We obtain the generalized Friedmann equations in the Universe with a Weylian boundary by considering the Friedmann-Lemaitre-Robertson-Walker metric. We consider the simultaneous decay of the scalar field, and of the creation of radiation, by appropriately splitting the general conservation equation through the introduction of the dissipation coefficient, which can depend on both the scalar field, and the Weyl vector. We consider three distinct warm inflationary models, in which the dissipation coefficients are chosen as different functions of the scalar field and of the Weyl vector. The numerical solutions of the cosmological evolution equations show that the radiation is created during the very early phases of expansion, and, after the radiation reaches its maximum value, the transition from an accelerating inflationary phase to a decelerating one takes place. Moreover, it turns out that the the Weyl vector, describing the boundary effects on the cosmological evolution, plays a significant role during the process of radiation creation.