ATLAS

Abstract:

The lifetime of the Bs meson is measured using the semileptonic decay Bs→Ds-+νX. The data sample consists of 19.3 pb-1 of pp̄ collisions at s=1.8 TeV collected by the Collider Detector at Fermilab during 1992-1993. There are 76±8 +Ds- signal events where the Ds is identified via the decay Ds-→φπ-, φ→K+K-. Using these events, the Bs meson lifetime is determined to be τs=1.42-0.23+0.27(stat)±0.11(syst) ps. A measurement of the Bs lifetime in a low statistics sample of exclusive Bs→J/ψ φ decays is also presented in this paper. © 1995 The American Physical Society.

Abstract:

The WW gauge boson couplings were measured using pp» +X (=e,) events at s=1.8 TeV observed with the D0 detector at the Fermilab Tevatron Collider. The signal, obtained from the data corresponding to an integrated luminosity of 13.8 pb-1, agrees well with the standard model prediction. A fit to the photon transverse energy spectrum yields limits at the 95% confidence level on the CP-conserving anomalous coupling parameters of -1.6< <1.8 (=0) and -0.6< <0.6 (=0). Similar limits are obtained for the CP-violating coupling parameters. © 1995 The American Physical Society.

Abstract:

We present a measurement of the mass of the W boson using data collected with the Collider Detector at Fermilab during the 1992-93 collider run at the Fermilab Tevatron. A fit to the transverse mass spectrum of a sample of 3268 W→μν events recorded in an integrated luminosity of 19.7 pb-1 gives a mass MWμ=80.310±0.205(stat)±0.130(syst) GeV/c2. A fit to 5718 W→eν events recorded in 18.2 pb-1 gives MWe=80.490±0.145(stat) ±0.175syst GeV/c2. Combining these results, accounting for correlated uncertainties, yields MW=80.410±0.180 GeV/c2. © 1995 The American Physical Society.

Abstract:

The D0 Collaboration reports on a search for the standard model top quark in pp̄ collisions at s=1.8TeV at the Fermilab Tevatron with an integrated luminosity of approximately 50 pb-1. We have searched for tt̄ production in the dilepton and single-lepton decay channels with and without tagging of b-quark jets. We observed 17 events with an expected background of 3.8±0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2×10-6 (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measured its mass to be 199-21+19 (stat) ±22 (syst) GeV/c2 and its production cross section to be 6.4±2.2 pb. © 1995 The American Physical Society.

Abstract:

We establish the existence of the top quark using a 67 pb-1 data sample of p̄p collisions at s=1.8 TeV collected with the Collider Detector at Fermilab (CDF). Employing techniques similar to those we previously published, we observe a signal consistent with tt̄ decay to WWbb̄, but inconsistent with the background prediction by 4.8σ. Additional evidence for the top quark is provided by a peak in the reconstructed mass distribution. We measure the top quark mass to be 176±8(stat)±10(syst) GeV/c2, and the tt̄ production cross section to be 6.8-2.4+3.6 pb. © 1995 The American Physical Society.