# Gravitational Memory in Generalized Proca Gravity

## TL;DR

This paper explores gravitational memory effects within the most general form of Generalized Proca gravity, analyzing how different background conditions influence the memory signals and their potential observational constraints.

## Contribution

It extends a unified framework for computing displacement memory to Generalized Proca gravity, identifying distinct classes of background conditions and analyzing their effects on gravitational memory.

## Key findings

- Dispersive scalar and vector modes in the massive case influence memory signals.
- Lorentz-violating massless case resembles Einstein-{ extperiodcentered}Aether theory dynamics.
- Memory signals can impose observational constraints on Lorentz violation.

## Abstract

We investigate the gravitational memory effect in the full Generalized Proca gravity, the most general metric theory including a gravitational Proca field with derivative self-interactions that still maintains second-order equations of motion. Building on our previous works on memory in other massless and massive metric theories, we extend a unified framework for computing displacement memory and apply it to Generalized Proca gravity. We identify two non-trivial physically distinct classes of background conditions of Generalized Proca theory within the assumption of asymptotic flatness: a Lorentz-invariant but massive case, and a Lorentz-violating, massless case. The former exhibits dispersive scalar and vector modes and allows a Horndeski-like treatment of memory, while the latter resembles the asymptotic dynamics of Einstein-{\AE}ther theory including the same Lorentz-breaking effects on displacement memory. In both cases, we derive the fully gauge invariant and dynamical second order action, derive the effective stress-energy tensor and study its contribution to the memory integral. We highlight the distinction between phase and group velocity in the tensor memory formula sourced by dispersive propagating modes. Finally, we re-emphasize how observational constraints on Lorentz violation may be imposed by the structure of the memory signal.