Warm inflation in hybrid metric-Palatini gravity under standard and irreversible thermodynamical approach

Iqra Shahid; Rabia Saleem; Hafiza Rizwana Kausar

doi:10.1140/epjc/s10052-023-11200-y

2022 Impact factor 4.4

Particles and Fields

Open Access

Eur. Phys. J. C (2023) 83: 85
https://doi.org/10.1140/epjc/s10052-023-11200-y

Regular Article - Theoretical Physics

Warm inflation in hybrid metric-Palatini gravity under standard and irreversible thermodynamical approach

Iqra Shahid¹, Rabia Saleem¹^b and Hafiza Rizwana Kausar²

¹ Department of Mathematics, COMSATS University Islamabad, Lahore Campus, Lahore, Pakistan
² Department of Mathematics, Faculty of Science and Technology, University of Central Punjab, Lahore, Pakistan

^b rabiasaleem@cuilahore.edu.pk

Received: 18 July 2022
Accepted: 4 January 2023
Published online: 28 January 2023

Abstract

The idea of hybrid metric-Palatini gravity (HMPG) is a blend of Einstein Hilbert (EH) action having non-linear function f(R) and linear scalar curvature R by Palatini gravity. The goal of this paper is to investigate the warm inflationary model (WIM) via standard and irreversible thermodynamical approach in gravity. We start our work by obtaining the field equations (FEs) for HMPG and then investigate the cosmic inflation in theory of gravity by looking at cosmic parameters such as slow-roll parameters, spectral index , running of spectral index and tensor-to-scalar ratio (r). Next, the early universe is considered as an open system. The thermodynamics and dynamical equations in gravity are applied to interacting cosmic fluid, which leads us to adapt the basic formalism of WIM. This analysis is done using Higgs Potential (HP). Numerical results of the thermodynamical equations such as scale factor (a(t)), scalar-field energy density and radiation energy density , number of scalar-field particles and temperature are derived and presented graphically using slow-roll approach and defining several dimensionless variables. From obtained results, we calculate cosmic parameters. In the end, we constraint the model parameters, and compare our calculated results to the Planck-2018 data.

© The Author(s) 2023

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