Dr Elizabeth Gallas

Abstract:

We performed a direct search for the anomalous ZZ and Z couplings by studying pp» +X (=e,) events at s=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 14.3 pb-1 (13.7 pb-1) for the electron (muon) channel, yields the following 95% confidence level limits on the anomalous CP-conserving ZZ couplings: |h30Z|<1.8 (h40Z=0) and |h40Z|<0.5 (h30Z=0), for a form-factor scale =500 GeV. Limits for the Z couplings and CP-violating couplings are also discussed. © 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:

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:

The results of a search for W boson pair production in pp» collisions at s=1.8 TeV with subsequent decay to dilepton (e,ee, and) channels are presented. One event is observed with an expected background of 0.56 0.13 events with an integrated luminosity of approximately 14 pb-1. Assuming equal strengths for the WWZ and WW gauge boson coupling parameters and, limits on the CP-conserving anomalous coupling constants are -2.6< <2.8 and -2.1< <2.1 at the 95% confidence level. © 1995 The American Physical Society.

Abstract:

We present new results on the search for the top quark in pp̄ collisions at s=1.8 TeV with an integrated luminosity of 13.5±1.6 pb-1. We have considered tt̄ production in the standard model using electron and muon dilepton decay channels (tt̄→eμ + jets, ee + jets, and μμ + jets) and single-lepton decay channels (tt̄→e + jets and μ + jets) with and without tagging of b quark jets. From all channels we have nine events with an expected background of 3.8±0.9. If we assume that the excess is due to tt̄ production, and assume a top mass of 180 GeV/ c2, we obtain a cross section of 8.2±5.1 pb. © 1995 The American Physical Society.