Bartel, W et al. (1982) Observation of a charge asymmetry in e+e− → μ+μ−. Physics Letters B, 108 (2). pp. 140-144. ISSN 0370-2693

The angular distribution and the s dependence of the total cross section for the process e+e− → μ+μ− have been measured using the JADE detector at PETRA. After radiative corrections, a forward-backward asymmetry of −(11.8±3.8) % was observed at an average centre of mass energy of 33.5 GeV. For comparison, an asymmetry of −7.8 % is expected on the basis of the standard Glashow-Salam-Weinberg model.