Order (alpha^2 Gamma, alpha^3 Gamma) Binding Effects in Orthopositronium Decay

Abstract

We present a new, simplified analysis of the low-energy electron-positron interaction, and use the resulting effective theory to calculate the binding effects that contribute to the decay rate, Gamma, of orthopositronium, through Order(alpha^3 ln(alpha) Gamma). We express the total decay rate in terms of the annihilation rate for a free electron and positron at threshold, which has just recently been computed to sufficient precision. Our result corrects errors in a previous analysis.

Comments: 6 pages, revtex. v2: higher order contributions included, references added. v3: check with muonium hyperfine splitting added