Cosmological Solutions from a Multi-Measure Model with Inflaton Field

TL;DR

This paper explores a modified gravity model with multiple scalar fields, demonstrating through numerical analysis that it can reproduce key cosmological epochs, including inflation, matter domination, and acceleration, under specific parameter conditions.

Contribution

It introduces a complex multi-measure gravity model with an inflaton field and shows its capability to replicate the Universe's evolution stages.

Findings

Model reproduces inflation, matter dominance, and acceleration.

Solutions occur within a narrow parameter range.

Parameter variation affects inflation duration.

Abstract

In a recent work, we demonstrated that a modified gravity model in which a scalar "darkon" field is coupled to both the standard Riemannian metric and to another non-Riemannian volume form is compatible with observational data from Supernovae Type Ia. Here, we investigate a more complicated model with an additional "inflaton" scalar field. We demonstrate numerically that the model can qualitatively reproduce the Universe inflation epoch, matter dominated epoch, and present accelerating expansion in a seamless way. We show that such solutions occur only when the model parameters are within a very particular range. The main numerical problem we are faced with is reproducing the extremely small time of the inflation epoch. Here, we present how the variation of some parameters affects this time.