Corrections to the Positronium Hyperfine Structure of Orderα2lnα−1

Abstract

We report a calculation of the $m{\alpha }^6\ln {\alpha }^{-1\mathrm{}}$ contributions to the triplet-singlet splitting of the positronium ground state. Our result, $\Delta \nu \left({\alpha }^6\ln {\alpha }^{-1\mathrm{}}\right)=\frac{1}{2}m{\alpha }^6\ln {\alpha }^{-1\mathrm{}}=46\mathrm{} \mathrm{MHz},$ shifts the theoretical prediction from two standard deviations below to two standard deviations above the most recent experimental value.