Effective Single Photon Decay Mode of Positronium Decay via Electroweak Interactions

TL;DR

This paper calculates the rare decay rate of positronium into a single photon and neutrinos via electroweak interactions, providing a precise standard model prediction for this elusive process.

Contribution

It presents the first detailed calculation of positronium decay into a photon and neutrinos mediated by electroweak interactions, including all neutrino channels.

Findings

Decay rate of positronium to photon and neutrinos: 1.72 x 10^{-19} s^{-1}

Electroweak interactions enable this rare decay mode

Provides a standard model benchmark for experimental searches

Abstract

We consider the decay of positronium to a neutrino-antineutrino accompanied by a single photon. Since the neutrino pair go undetected, this appears as a single photon decay of positronium. These decay channel are mediated through the exchange of the massive $W$ and $Z$ vector bosons of the electroweak interaction. After summing over the various neutrino channels, the standard model calculation yields the rate for such a single photon decay process of $\Gamma_{Ps \rightarrow \gamma}$ = 1.72 $\times 10^{-19}$ s$^{-1}$.