alpha^2 corrections to parapositronium decay

TL;DR

This paper calculates two-loop QED corrections to parapositronium decay, finding small non-logarithmic alpha^2 effects, suggesting the orthopositronium lifetime puzzle is unlikely due to large QED corrections.

Contribution

It provides the first precise calculation of two-loop QED corrections to parapositronium decay rate, clarifying their small impact compared to previous estimates.

Findings

Calculated decay rate as 7989.64(2)/microsec.

Found non-logarithmic O(alpha^2) corrections to be small.

Concluded large QED corrections are unlikely to resolve the orthopositronium puzzle.

Abstract

Two-loop QED corrections to the decay rate of parapositronium (p-Ps) into two photons are presented. We find Gamma(p-Ps --> 2 photons) = 7989.64(2)/microsec. The non-logarithmic O(alpha^2) corrections turn out to be small, contrary to some earlier estimates. We speculate that the so-called ``orthopositronium lifetime puzzle'' will not likely be solved by large QED corrections.