Gravitational memory effects in Tachyon gravity

TL;DR

This paper investigates how a non-minimally coupled massless Tachyon field influences gravitational memory, soft theorems, and symmetries at null infinity, revealing new polarization modes and modifications to known formulas.

Contribution

It introduces a model with Tachyon gravity affecting gravitational memory and soft theorems, including the addition of a breathing polarization mode and modified mass loss.

Findings

Tachyon field adds a breathing polarization mode to gravitational waves.

The presence of Tachyon modifies the Bondi mass loss formula.

Derived new soft factors involving soft graviton and scalar radiation.

Abstract

In this paper, we explore how a massless Tachyon field, when non-minimally coupled to gravity, affects gravitational memory, soft theorems, and symmetries near null infinity. We set up the model using both the Jordan and Einstein frames, work out the equations of motion and study the behavior of fields at large distances with the Bondi-Sachs gauge. The Tachyon adds a ``breathing'' polarization mode to the gravitational radiation, which modifies the Bondi mass loss formula and leaves a trace in the displacement memory effect. We also derived the leading and subleading soft factors, involving the radiation of a soft graviton or a soft scalar.