Leading logarithmic contribution to the second-order lamb shift induced by the loop-after-loop diagram.
The contribution of order alpha(2)(Zalpha)(6)ln (3)(Zalpha)(-2) to the ground-state Lamb shift in hydrogen induced by the loop-after-loop diagram is evaluated analytically. An additional contribution of this order is found compared to the previous calculation by Karshenboim [Sov. Phys. JETP 76, 541 (1993)]. As a result, agreement is achieved for this correction between different numerical and analytical methods.
Yerokhin
V A
VA
Department of Physics, St. Petersburg State University, Oulianovskaya 1, Petrodvorets, St. Petersburg 198904, Russia.