IMPROVED THEORY OF THE MUONIUM HYPERFINE-STRUCTURE

Terms contributing to the hyperfine structure of the muonium ground st ate at the level of few tenths of kHz have been evaluated. The alpha2( Zalpha) radiative correction has been calculated numerically to the pr ecision of 0.02 kHz. Leading ln(Zalpha) terms of order alpha4-n(Zalpha )n,n = 1,2,3, and some relativistic corrections have been evaluated an alytically. The theoretical uncertainty is now reduced to 0.17 kHz. At present, however, it is not possible to test QED to this precision be cause of the 1.34 kHz uncertainty due to the muon mass.