Two-photon decay of para-positronium within a composite approach

TL;DR

This paper investigates the two-photon decay of para-positronium using a composite quantum field theoretical model, emphasizing the vertex function's impact on decay rates and exploring implications for other decay channels.

Contribution

It introduces a composite approach to positronium decay, incorporating the Weinberg compositeness condition and vertex function effects on decay rates.

Findings

Vertex function choices influence decay rate calculations.

The approach provides insights into other positronium decay channels.

Framework can be extended to study various positronium states.

Abstract

The decay of the para-positronium into two photons is studied in the framework of a composite Quantum Field Theoretical approach. This amounts to the evaluation of the electron-positron dressing together with the Weinberg compositeness condition for the positronium and the triangle-shaped diagram with virtual electrons circulating in it, leading to the two-photon final state. An important role is played by the positronium-electron-positron vertex, which is linked to the wave function of the para-positronium. We show how possible choices for the vertex function affect the $\gamma \gamma$ decay rate. Outlooks to other decay channels and to other positronia are presented.