# QED and Fundamental Symmetries in Positronium Decays

## TL;DR

This paper reviews how positronium decay experiments can test fundamental symmetries and constrain new physics, emphasizing the importance of precision measurements involving electrons and photons.

## Contribution

It provides a comprehensive analysis of positronium decay processes in relation to fundamental symmetry tests and existing precision constraints.

## Key findings

- Positronium decay measurements can test charge-parity-time symmetry violations.
- Current experimental bounds limit possible new physics contributions.
- Precision observables involving electrons and photons complement positronium decay tests.

## Abstract

We discuss positronium decays with emphasis on tests of fundamental symmetries and the constraints from measurements of other precision observables involving electrons and photons.