Inflation and reheating in quadratic metric-affine gravity with derivative couplings

TL;DR

This paper explores inflation and reheating in a quadratic metric-affine gravity model with derivative couplings, showing compatibility with observations and potential for high reheating temperatures.

Contribution

It introduces a quadratic metric-affine gravity framework with derivative couplings, analyzing inflationary predictions and reheating potential without proposing a specific reheating mechanism.

Findings

Inflation predictions align with observational constraints.

Adjustments can increase spectral index and decrease tensor-to-scalar ratio.

Maximum reheating temperature can reach approximately 3×10^{15} GeV.

Abstract

Within the framework of metric-affine theories of gravity, where both the metric and connection are treated as independent variables, we consider actions quadratic in the Ricci scalar curvature coupled non-minimally to a scalar field through derivative couplings. Our analysis delves into the inflationary predictions, revealing their consistency with the latest observational constraints across a wide range of parameters. This compatibility permits adjustments such as an increase in the spectral index and a reduction in the tensor-to-scalar ratio. While we do not propose a specific reheating mechanism, our analysis demonstrates that within the quadratic model of inflation, the maximum reheating temperature can reach $\sim 3\times10^{15}\, {\rm GeV}$.