Gauss–Bonnet inflation: Perturbations, reheating and observational constraints

In this paper, we present a comprehensive analysis of slow-roll inflation incorporating Gauss–Bonnet corrections within modified gravity frameworks. The model features a nonminimal coupling between the inflaton field and the Gauss–Bonnet invariant, with the coupling function [Formula: see text] inversely proportional to the scalar potential [Formula: see text]. We derive the complete set of background equations, slow-roll parameters and cosmological perturbations within this framework. The scalar spectral index [Formula: see text] and tensor-to-scalar ratio r are computed for a class of exponential-potential models, showing excellent agreement with Planck 2018 and ACT 2024 observational constraints. Furthermore, we extend the analysis to include reheating dynamics, primordial non-Gaussianity and comparison with latest CMB data. Our results demonstrate that Gauss–Bonnet corrected inflation provides a viable framework compatible with current cosmological data while offering testable predictions for future observations, particularly in light of recent tensions between different CMB experiments.