arXiv subjects

S. Abachi

Publications and source records attributed to S. Abachi.

21 records · Page 2Linked to original sources

arXiv1995

Measurement of the $ZZγ$ and $Zγγ$ Couplings in $p\bar p$ Collisions at $\sqrt{s} = 1.8$ TeV

We have directly measured the ZZ-gamma and Z-gamma-gamma couplings by studying p pbar --> l+ l- gamma + X, (l = e, mu) events at the CM energy of 1.8$ TeV with the D0 detector at the Fermilab Tevatron Collider. A fit to the transverse energy spectrum of the photon in the signal events, based on the data set corresponding to an integrated luminosity of 13.9 pb^-1 ($13.3 pb^-1) for the electron (muon) channel, yields the following 95% confidence level limits on the anomalous CP-conserving ZZ-gamma couplings: -1.9 < h^Z_30 < 1.8 (h^Z_40 = 0), and -0.5 < h^Z_40 < 0.5 (h^Z_30 = 0), for a form-factor scale Lambda = 500 GeV. Limits for the Z-gamma-gamma$ couplings and CP-violating couplings are also discussed.

hep-ex↗

arXiv1995

Observation of the Top Quark

The DO collaboration reports on a search for the Standard Model top quark in pbar-p collisions at Sqrt(s)=1.8TeV at the Fermilab Tevatron, with an integrated luminosity of approximately 50pb-1. We have searched for t-tbar 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 2.0E-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 measure its mass to be 199^+19_21 (stat.)+/- 22 (syst.)GeV/c**2 and its production cross section to be 6.4 +/- 2.2 pb.

hep-ex↗

arXiv1994

Search for High Mass Top Quark Production in p anti-p Collisions at S**(1/2) = 1.8 TeV

We present new results on the search for the top quark in p anti-p collisions at S**(1/2) = 1.8 TeV with an integrated luminosity of 13.5 +- 1.6 pb**(-1). We have considered t anti-t production in the Standard Model using electron and muon dilepton decay channels (t anti-t -> e mu + jets, e e + jets, and mu mu + jets) and single-lepton decay channels (t anti-t -> e + jets and mu + jets) with and without tagging of b quark jets. From all channels, we have 9 events with an expected background of 3.8 +- 0.9. If we assume that the excess is due to t anti-t production, and assuming a top mass of 180 GeV/c**2, we obtain a cross section of 8.2 +- 5.1 pb.

hep-ex↗