Parapositronium can decay into three photons

TL;DR

This paper calculates the decay rate and spectrum of parapositronium decaying into three photons via weak interaction, revealing a much smaller branching ratio than previously estimated, and highlighting charge conjugation violation.

Contribution

It provides the first detailed calculation of the weak-interaction-induced decay of parapositronium into three photons, correcting prior overestimations.

Findings

Decay rate is fifty orders of magnitude smaller than previous estimates.

Decay proceeds through weak interaction, violating charge conjugation symmetry.

Branching ratio is extremely suppressed, making detection challenging.

Abstract

We calculate the decay rate and spectrum for the decay of parapositronium into three photons. This process violates charge conjugation symmetry. It is forbidden within quantum electrodynamics but proceeds through the weak interaction. The branching ratio we find is fifty orders of magnitude smaller than the previous estimate.