New value of m(mu)/m(e) from muonium hyperfine splitting.
The complete contribution to the muonium hyperfine splitting of relative order alpha(3)(m(e)/m(mu))lnalpha is calculated. The result is much smaller than suggested by a previous estimate and leads to a 2sigma upward shift of the most precise value for the muon-electron mass ratio. Analogous contributions are calculated for the positronium hyperfine splitting, where a discrepancy with experiment remains.
Hill
R J
RJ
Newman Laboratory of Nuclear Studies, Cornell University, Ithaca, NY 14853, USA.