We evaluate the magnetic moment μ=geħ/2${\mathit{m}}_{\mathrm{\tau }}$c of the τ lepton. This is interesting from a purely theoretical point of view, although an experimental measurement, though difficult, may be possible in the future. Our result, including strong- and weak-interaction contributions, which are large, is ${\mathit{a}}_{\mathrm{\tau }}$=(g-2)/2=11 773(3)×${10}^{\mathrm{-}7}$.

• Received 3 May 1991

DOI:https://doi.org/10.1103/PhysRevLett.67.668