QED calculation of the interelectron interaction in two- and three-electron ions

Screened Self-energy Correction to the 2p[sub 3∕2]–2s Transition Energy in Li-Like Ions

“…[13,14] for the 2p 3/2 state. An independent evaluation of the two-photon exchange correction for Li-like ions was performed by Andreev et al [15,16]. A calculation of the screened self-energy correction was carried out in Ref.…”

Measurement of the Two-Loop Lamb Shift in LithiumlikeU89+

“…Rigorous calculations of all two-electron contributions of order α 2 have recently been completed, including the two-photon exchange term as well as estimates of higher-order photon exchange contributions [4,5,16]. Adding these to the one-photon exchange, first order QED, nuclear recoil, nuclear polarization, and one-electron finite size contributions yields a value for the 2s 1/2 -2p 1/2 transition energy that misses only the twoloop Lamb shift contribution.…”

“…[4], Sapirstein and Cheng [5], and Andreev et al [16] is listed in Table II. The differences among the three values in Table II arise from differences in the calculated values of the twoelectron self energy and the estimated size of the three-photon exchange term, as discussed by Sapirstein and Cheng [5].…”

Testing high-Z QED with SuperEBIT: An estimate of the two-loop Lamb shift based on a measurement of the – transition in

“…These include the two-photon exchange term as well as estimates of higher-order photon exchange contributions (Yerokhin et al, 2000;Andreev et al, 2001;Sapirstein and Cheng, 2001). Adding these to the onephoton exchange, first order QED, nuclear recoil, nuclear polarization, and one-electron finite size contributions yields a value for the 2s 1=2 -2p 1=2 transition energy that misses only the two-loop Lamb shift contribution.…”