A search for rare B meson decays at the CERN S p anti-p S collider

We report on a search for the decays B0 --> mu+mu-, B --> mu+mu-X and B(d)0 --> mu+mu-K0*, which are expected to be rare if mediated by flavor changing neutral currents. Using data collected during the 1984-1989 CERN ppBAR Collider runs, the UA1 search was carried out using mu+mu- events with 3.9 mu+mu- of 8.3 x 10(-6), for B --> mu+mu-X of 5.0 x 10(-5), and for B(d)0 --> mu+mu-K0* of 2.3 x 10(-5). Implications for upper limits on the t-quark mass are discussed

Measurement of the ratio R = sigma(w) Br (W) ---> mu neutrino) / sigma(Z) Br (Z ---> mu mu) and gamma(W) total at the CERN proton - anti-proton collider

An analysis of W and Z boson production at UA1, using 4.66 pb-1 of data from the 1988 and 1989 CERN ppBAR Collider runs at square root of s = 0.63 TeV, yields R = sigma(w)Br(W --> mu-v)/sigma(z)Br(z --> mu-mu) = 10.4(-1.5)(+1.8)(stat.) +/- 0.8(syst). We find R = 9.5(-1.0)(+1.1)(stat. + syst.) when combining all available UA1 data, in both the electron and muon channel, taken in the period 1983-1989. In the framework of the standard model, the value of R is used to infer the total width of the W boson, I(w) (tot) = 2.18(-0.24)(+0.26) (exp.) +/- 0.04 (theory) GeV/c2

Limits on t quark decay into charged Higgs from a direct search at the CERN p anti-p collider

A search for t-quark decay into charged Higgs, t --> H+b, with the charged Higgs decaying via the H+ --> tau+nu-tau mode, has been done in proton-antiproton collisions at square root s = 0.63 TeV with the UA1 experiment. No evidence for this decay has been observed. Mass limits at 95% and 90% CL for the t-quark and the charged Higgs are presented. The results have also been interpreted in terms of the tan beta-parameter of a two-doublet Higgs sector