# Universality of the Poincar\'e gravitational form factor constraints

## TL;DR

This paper proves that the zero momentum-transfer limits of key gravitational form factors are universal and independent of the choice of relativistic spin states, stemming solely from Poincaré covariance.

## Contribution

It establishes the universality of gravitational form factor constraints across different relativistic spin state conventions and mass conditions.

## Key findings

- Zero momentum-transfer limits are independent of spin state conventions.
- Constraints are unaffected by whether states are massive or massless.
- Results rely solely on Poincaré covariance principles.

## Abstract

Relativistic spin states are convention dependent. In this work we prove that the zero momentum-transfer limits of the leading two form factors in the decomposition of the energy-momentum tensor matrix elements are independent of this choice. In particular, we demonstrate that these constraints are insensitive to whether the corresponding states are massive or not, and that they arise purely due to the Poincar\'e covariance of the states.