Strong Equivalence, Lorentz and CPT Violation, Anti-Hydrogen Spectroscopy and Gamma-Ray Burst Polarimetry

TL;DR

This paper explores potential violations of fundamental symmetries like Lorentz and CPT in quantum electrodynamics, proposing astrophysical and atomic spectroscopy tests to detect such effects, including polarization rotation and atomic energy shifts.

Contribution

It constructs and analyzes Lorentz and CPT violating Lagrangians for QED and suggests novel experimental tests in astrophysics and atomic physics to detect symmetry violations.

Findings

Predicted birefringent rotation of polarized radiation from astrophysical sources.

Proposed precision spectroscopy of hydrogen and anti-hydrogen to detect energy level shifts.

Identified potential observable effects in gamma-ray burst polarimetry and atomic transitions.

Abstract

The strong equivalence principle, local Lorentz invariance and CPT symmetry are fundamental ingredients of the quantum field theories used to describe elementary particle physics. Nevertheless, each may be violated by simple modifications to the dynamics while apparently preserving the essential fundamental structure of quantum field theory itself. In this paper, we analyse the construction of strong equivalence, Lorentz and CPT violating Lagrangians for QED and review and propose some experimental tests in the fields of astrophysical polarimetry and precision atomic spectroscopy. In particular, modifications of the Maxwell action predict a birefringent rotation of the direction of linearly polarised radiation from synchrotron emission which may be studied using radio galaxies or, potentially, gamma-ray bursts. In the Dirac sector, changes in atomic energy levels are predicted which may be probed in precision spectroscopy of hydrogen and anti-hydrogen atoms, notably in the Doppler-free, two-photon $1s-2s$ and $2s-nd (n \sim 10)$ transitions.