# Gravity and Nonlinear Symmetry Realisation

## TL;DR

This paper explores nonlinear symmetry realization in gravity, identifying a unique model for massless spin-2 states that differs from general relativity by describing states with well-defined mass that do not interact linearly with matter.

## Contribution

It introduces a novel nonlinear symmetry realization model for gravity that distinguishes between gravitational states with and without matter interaction.

## Key findings

- Identifies a specific nonlinear realization model suitable for massless spin-2 states.
- Shows this model describes states with well-defined mass that do not interact linearly with matter.
- Highlights the need to differentiate gravitational states based on their interaction with matter.

## Abstract

Application of nonlinear symmetry realisation technique to gravity is studied. We identify the simplest extensions of the Poincare group suitable for nonlinear realisation. Among them only one model is suitable for description of massless spin-2 states. This model, unlike general relativity, describes states with well-defined mass that lack a linear interaction with the matter states. We argue that this phenomenon points on a necessity to draw a distinction between gravitational states with well defined masses and states that participate in interaction with matter.