The 2S1/2–2P1/2 Lamb shift in He+

Abstract

The current theoretical status of the Lamb shift in He+ is discussed. Recent calculations of two-loop binding corrections to the Lamb shift significantly shift the theoretical value of the "classic" Lamb shift in He+, i.e., of the 2S1/2–2P1/2 interval. In this brief article, we present a new (theoretical) value for this interval that reads 14 041.474(42) MHz. The theoretical uncertainty is reduced as well as the discrepancy between theory and experiment. Planned measurements should be of help in further elucidating the situation.PACS Nos.: 31.15.–p, 12.20.Ds