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.

• Received 5 April 1993

DOI:https://doi.org/10.1103/PhysRevA.48.R15