Cosmology in scalar tensor theory and asymptotically de-Sitter Universe

TL;DR

This paper explores cosmological models derived from scalar-tensor theories linked to higher-dimensional frameworks, demonstrating a transition from decelerated to accelerated expansion leading to an asymptotically de-Sitter universe.

Contribution

It presents a novel cosmological solution within scalar-tensor theories that naturally transitions from decelerated to accelerated expansion, connecting higher-dimensional theories to observable late-time acceleration.

Findings

Universe transitions from decelerated to accelerated expansion.

Dilaton field decreases and stabilizes, leading to Einstein gravity.

Model predicts a positive cosmological constant at late times.

Abstract

We have investigated the cosmological scenarios with a four dimensional effective action which is connected with multidimensional, supergravity and string theories. The solution for the scale factor is such that initially universe undergoes a decelerated expansion but in late times it enters into the accelerated expansion phase. Infact, it asymptotically becomes a de-Sitter universe. The dilaton field in our model is a decreasing function of time and it becomes a constant in late time resulting the exit from the scalar tensor theory to the standard Einstein's gravity. Also the dilaton field results the existence of a positive cosmological constant in late times.