Theoretical energies of low-lying states of light helium-like ions

A rigorous quantum electrodynamical calculation is presented for energy levels of the 1 S-1, 2 S-1, 2 S-3, 2 P-1(1), and 2 P-3(0,1,2) states of helium- like ions with the nuclear charge Z = 3, ... , 12. The calculational approach accounts for all relativistic, quantum electrodynamical, and recoil effects up to orders m alpha(6) and m(2) / M alpha(5), thus advancing the previously reported theory of light helium-like ions by one order in alpha.