Inflationary Dynamics of Mutated Hilltop Inflation in Einstein-Gauss-Bonnet Gravity Under New Slow-Roll Approximations with Generalised Reheating

Abstract

The advancement in the observational cosmology of the early universe such as Cosmic Microwave Background (CMB) observations, puts severe constraints on the inflationary models. Many inflationary models have been ruled out by CMB, nevertheless the models ruled out in standard cold inflationary scenarios can be resurrected in modified gravity models. In this regard we examine the dynamics of inflation within the framework of Einstein-Gauss-Bonnet (EGB) Gravity using the new slow-roll approximation methods proposed in Pozdeeva et al. (2024). We consider the Mutated Hilltop inflation model (Pal et al., 2010; Pinhero and Pal, 2019) due to its origin from super-gravity, a naturally perfect choice to study the impact of EGB on inflationary observables such as tensor-to-scalar ratio ($r$) and scalar spectral index ($n_s$). The period of reheating following the inflationary phase is also examined, and for the {\it Planck'18} permitted values of $n_s$, constraints on the reheating temperature ($T_{re}$) are computed for various equations of states during reheating ($\omega_{re}$).