Anomalous positron excess from Lorentz-violating QED

TL;DR

This paper proposes that a Lorentz-violating background from pseudoscalar condensates modifies QED, allowing high-energy photons to decay into pairs, potentially explaining cosmic ray anomalies and offering a new probe in heavy ion collisions.

Contribution

It introduces a Lorentz-violating QED model with a pseudoscalar background causing photon decay, providing a novel explanation for cosmic ray observations.

Findings

High-energy photon decay into pairs depends on the pseudoscalar mass

The mechanism explains the absence of antiprotons in cosmic rays

Potential application as a probe in heavy ion collisions

Abstract

We entertain the idea that a suitable background of cold (very low momentum) pseudoscalar particles or condensate, may trigger a background that effectively generates Lorentz-invariance violation. This aether-like background induces a Chern-Simons modification of QED. Physics is different in different frames and, in the rest frame of the pseudoscalar background, high momentum photons can decay into pairs. The threshold for such decay depends quadratically on the rest mass of the particles. This mechanism could explain in a natural way why antiprotons are absent in recent cosmic ray measurements. A similar signal could be used as a probe of pseudoscalar condensation in heavy ion collisions.