What can one learn with muons about atomic physics?

Abstract

The atomic physics of a hydrogen-like atom is still an interesting field. With this simplest of all possible atomic systems, one gets (besides many other quantities) information about the fundamental question : What is the "true" interaction between charged particles? Although these atoms are relatively simple, one has not been able to study experimentally more than a few very light ones, namely up to C + 5 .Lamb shift experiments obtain very precise energy differences between nsli2 and np,,, electronic states, which should be degenerate according to the Dirac equation. The contributions to the best known splitting which is the 2s -2p,,, difference in hydrogen are given in column 1 of Table I. After more than 20 years, (2s -2p,,,), p-Pb (1s) and .~-p b ( S g~,~-4f5d energyeigenvalue OK t r a n s i t i o n energy Dirac e q u a t i o n p o i n t nucleus f i n i t e s i z e e f f e c t Znd o r d e r s e l f -e n e r g y znd order vacuumpolar i s a t i o n pnd order remainder qch order s e l f -e n e r g y bth order Vacuumpolarisation