B-production and the evidence for B0-anti B0 mixing at the CERN panti-p collider

Muon pair production has been observed at the CERN panti-p-collider at c.m. energies of 540 and 630 GeV. The events are interpreted in terms of the Drell-Yan mechanism, J/ψ and υ-decays of semileptonic decays of heavy quark pairs. The inclusive b-quark production cross-section is large (several μb). The properties of the dimuon events, which are dominated by b anti b production, are in excellent agreement with QCD calculations, except for the large value of R, the ratio of like sign to unlike sign events. The most likely explanation of the observed R = 0.46 ± 0.07 ± 0.03 is the existence of B0-anti B0 oscillations. This is not at variance with e+e- data, provided the oscillations occur between b anti s and anti b s states. 14 figs.; 9 refs