Primordial Gravitational Waves in Generalized Palatini Gravity

TL;DR

This paper investigates how a geometric Proca field in extended Palatini gravity influences gravitational waves, suggesting detectable signatures that could indicate non-Riemannian gravity if observed.

Contribution

It demonstrates that the geometric Proca field in extended Palatini gravity leaves observable imprints on gravitational waves, providing potential evidence for non-Riemannian gravity.

Findings

Geometric Proca field significantly alters gravitational wave signals.

Gravitational wave energy density could be detectable with future GW detector upgrades.

Results suggest possible observational evidence for non-Riemannian gravity.

Abstract

Extended Palatini gravity is the metric-affine gravity theory characterized by zero torsion, nonzero metricity and a quadratic of the antisymmetric Ricci curvature. It reduces dynamically to general relativity plus a geometric Proca field. In this work, we study imprints of the geometric Proca field in the gravitational waves . Our results show that the geometric Proca leaves significant signatures in the gravitational wave signal, and gravitational wave energy density is large enough to be detectable by the next upgrade of the existing GW detectors. Our results, if confirmed observationally, will be an indication that the gravity could well non-Riemannian in nature.