Gravitational Memory Effect in the Massless Vector Field

TL;DR

This paper investigates how a massless vector field influences gravitational memory effects and infrared structure in asymptotically flat spacetimes, revealing modifications to known GR memory expressions and persistent vector memory phenomena.

Contribution

It introduces a detailed analysis of vector field effects on gravitational memory, deriving modified memory expressions and identifying gauge-invariant vector memory effects.

Findings

Modified displacement, spin, and CM memory expressions due to vector fields

Persistent vector memory effects linked to angular vector modes

Continuous reduction to GR when vector coupling is removed

Abstract

We analyze the infrared structure and memory effects of a massless vector tensor theory with non minimal curvature coupling in asymptotically flat spacetimes. Using Bondi Sachs expansions, we identify the independent radiative data and derive the effective Bondi mass aspect, whose balance law receives an additional positive definite flux from the vector sector. This leads to modified displacement, spin, and center of mass memory (CM) expressions, where the gravitational contributions retain their General Relativity (GR) form and the vector field enters only through well defined flux terms. We also describe persistent vector memory effects associated with the leading angular vector mode, which are gauge invariant but do not affect the leading tidal observables. The BMS transformations act kinematically as in GR. Tensor vacua remain supertranslation degenerate, whereas the vector vacuum, defined by the vanishing vector field, is nondegenerate. All results reduce continuously to GR when the coupling is removed, isolating the precise channels through which vector curvature interactions modify the infrared dynamics.