title: New value of m(mu)/m(e) from muonium hyperfine splitting.
abstract: 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.
authors.affiliation: Newman Laboratory of Nuclear Studies, Cornell University, Ithaca, NY 14853, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Hill