Bounding CPT- and Lorentz-Violating Parameters in a Standard-Model Extension

TL;DR

This paper reviews a theoretical framework extending the standard model to include potential CPT and Lorentz violations, discusses experimental bounds on these violations, and summarizes current experimental constraints.

Contribution

It develops a comprehensive theoretical framework for CPT and Lorentz violation and compiles existing experimental bounds within this context.

Findings

Established bounds from Penning-trap experiments with electrons and positrons

Summarized bounds from experiments with protons and antiprotons

Reviewed potential bounds from hydrogen and antihydrogen experiments

Abstract

A general theoretical framework that incorporates possible CPT and Lorentz violation in an extension of the standard model and in quantum electrodynamics has been developed over the last decade. The framework originates in the idea that CPT and Lorentz symmetry could be broken spontaneously in a more fundamental theory such as string theory. These symmetry violations are described in the standard-model extension by small terms in the Lagrangian. Various experiments can bound these quantities. They include Penning-trap experiments with electrons and positrons, Penning-trap experiments with protons and antiprotons, and possible experiments with hydrogen and antihydrogen in traps or beams. I will review aspects of the theory, outline estimated bounds attainable in specific experiments, and present known bounds from completed experiments.