Testing Theories of Gravity with a Spherical Gravitational Wave Detector

TL;DR

This paper explores how a spherical gravitational wave detector can differentiate between gravity theories by analyzing vibrational modes and their relation to Newman-Penrose parameters, with toroidal modes serving as a veto.

Contribution

It introduces a method to discriminate gravity theories using spherical detectors by relating vibrational modes to theoretical parameters, including a veto mechanism using toroidal modes.

Findings

Spheroidal modes can reveal the spin content of gravity theories.

Toroidal modes are not excited by metric gravitational waves and can be used as a veto.

The approach links vibrational measurements to Newman-Penrose parameters.

Abstract

We consider the possibility of discriminating different theories of gravity using a recently proposed gravitational wave detector of spherical shape. We argue that the spin content of different theories can be extracted relating the measurements of the excited spheroidal vibrational eigenmodes to the Newman-Penrose parameters. The sphere toroidal modes cannot be excited by any metric GW and can be thus used as a veto.