Energy corrections of ordermc2α6lnα in helium

Abstract

Quantum-electrodynamic corrections of O(${\mathit{mc}}^2$ ${\mathrm{\alpha }}^6$lnα) to the electron-electron interaction in helium are evaluated for several states. The additional energy shift, which is an order of α smaller than the leading Araki-Sucher terms, raises the predicted energy of the 1s2s ${}_{}{}^1{}_{}{}^{}$ ${\mathit{S}}_0$ state by 2.49 MHz to -960 332 039.43(18) MHz relative to ${\mathrm{He}}^{+}$(1s). The new value significantly alters the comparison with recent high-precision experiments.