Cosmic Acceleration in an Extended Brans-Dicke-Higgs Theory

TL;DR

This paper explores an extended scalar-tensor gravity model with two interacting scalar fields, aiming to explain late-time cosmic acceleration and its transition from deceleration, using observational data for constraints.

Contribution

It introduces a novel interaction between Brans-Dicke and Higgs fields in a scalar-tensor framework and analyzes its cosmological implications with observational constraints.

Findings

Model can describe late-time acceleration with a smooth transition from deceleration.

Scalar field profiles are reconstructed as functions of redshift.

Constraints on model parameters are obtained from observational data.

Abstract

We consider an extended scalar-tensor theory of gravity where the action has two interacting scalar fields, a Brans-Dicke field which makes the effective Newtonian constant a function of coordinates and a Higgs field which has derivative and non-derivative interaction with the lagrangian. There is a non-trivial interaction between the two scalar fields which dictates the dominance of different scalar fields in different era. We investigate if this setup can describe a late-time cosmic acceleration preceded by a smooth transition from deceleration in recent past. From a cosmological reconstruction technique we find the scalar profiles as a function of redshift. We find the constraints on the model parameters from a Markov Chain Monte Carlo analysis using observational data. Evolution of an effective equation of state, matter density contrast and thermodynamic equilibrium of the universe are studied and their significance in comparison with a LCDM cosmology is discussed.