# Gluonic Lorentz violation and chiral perturbation theory

## TL;DR

This paper applies chiral perturbation theory to the QCD sector of the Standard-Model Extension to investigate Lorentz violation in strong interactions, deriving effective Lagrangians and setting experimental limits.

## Contribution

It develops the first chiral effective Lagrangian for Lorentz-violating gluonic operators and derives new constraints from nucleon and nuclear experiments.

## Key findings

- Derived the Lorentz-violating nucleon self energy.
- Established the first limits on gluonic Lorentz-violating parameters.
- Proposed using nucleon-nucleon potentials for experimental tests.

## Abstract

By applying chiral-perturbation-theory methods to the QCD sector of the Lorentz-violating Standard-Model Extension, we investigate Lorentz violation in the strong interactions. In particular, we consider the CPT-even pure-gluon operator of the minimal Standard-Model Extension. We construct the lowest-order chiral effective Lagrangian for three as well as two light quark flavors. We develop the power-counting rules and construct the heavy-baryon chiral-perturbation-theory Lagrangian, which we use to calculate Lorentz-violating contributions to the nucleon self energy. Using the constructed effective operators, we derive the first stringent limits on many of the components of the relevant Lorentz-violating parameter. We also obtain the Lorentz-violating nucleon-nucleon potential. We suggest that this potential may be used to obtain new limits from atomic-clock or deuteron storage-ring experiments.