Early inflation in Gauss–Bonnet gravity coupled with a scalar field in an inverse-square potential

Abstract We investigate early inflation in Einstein Gauss–Bonnet gravity with a scalar field evolving in a plateau modified inverse square potential and non-minimally coupled to the Gauss–Bonnet invariant through an exponentially saturating coupling function. Within the slow-roll approximation, we derive the scalar spectral index, tensor to scalar ratio, and propagation speed of primordial tensor perturbations. Numerical integration of the background equations confirms the existence of stable inflationary trajectories and a graceful exit from the early inflationary phase. In the weak coupling regime, the model reproduces the standard plateau attractor behavior while generating controlled corrections in the tensor sector governed primarily by the ratio $$\frac{\lambda }{b}$$ λ b and the effective coupling combination $$\xi _0 V_0$$ ξ 0 V 0 . The predicted scalar spectral index and tensor to scalar ratio remain compatible with current CMB constraints, while the tensor sector remains free from ghost and gradient instabilities. It is shown that the higher curvature effects can produce a controlled modification of the primordial tensor perturbations without spoiling the successful scalar sector predictions from the plateau inflation.