Calculation of the discrete-spectrum Lamb-shift contribution in atomic hydrogen

By applying the exact transition matrix elements, which were evaluated in our preceding paper, unrenormalized and renormalized Lamb-shift contributions stemming from individual discrete states as well as from the whole discrete spectrum are calculated in the case of the states 1S, 2S and 2P. For the first time to our knowledge, it is pointed out that the unrenormalized discrete spectrum contribution is completely finite and thus conceptual clarifications in the renormalization procedure are achieved.