Dr Elizabeth Gallas

Abstract:

A study of the particle multiplicity between jets with large rapidity separation has been performed using the D0 detector at the Fermilab Tevatron pp^¯ Collider operating at √s = 1.8 TeV. A significant excess of low-multiplicity events is observed above the expectation for color-exchange processes. The measured fractional excess is 1.07±0.10(stat)^+0.25−0.13(syst)%, which is consistent with a strongly interacting color-singlet (colorless) exchange process and cannot be explained by electroweak exchange alone. A lower limit of 0.80% (95% C.L.) is obtained on the fraction of dijet events with color-singlet exchange, independent of the rapidity gap survival probability. © 1996 The American Physical Society.

Abstract:

A measurement of the mass of the W boson is presented based on a sample of 5982 W → eν decays observed in pp^¯ collisions at √s = 1.8 TeV with the D0 detector during the 1992-1993 run. From a fit to the transverse mass spectrum, combined with measurements of the Z boson mass, the W boson mass is measured to be MW = 80.350 ± 0.140(stat) ± 0.165(syst) ± 0.160(scale) GeV/c². © 1996 The American Physical Society.

Abstract:

We present results from a search for anomalous WW and WZ production in pp^¯ collisions at √s = 1.8 TeV. We used pp^¯ → evjjX events observed during the 1992-1993 run of the Fermilab Tevatron collider, corresponding to an integrated luminosity of 13.7 ± 0.7pb⁻¹. A fit to the transverse momentum spectrum of the W boson yields direct limits on the CP-conserving anomalous WWγ and WWZ coupling parameters of −0.9 < Δk < 1.1 (with λ = 0) and −0.6 < λ < 0.7 (with Δk = 0) at the 95% confidence level, for a form factor scale Λ = 1.5 TeV, assuming that the WWγ and WWZ coupling parameters are equal. © 1996 The American Physical Society.

Abstract:

We present a search for pair produced top squarks, the supersymmetric partners of the top quark, using the D0 detector at the Fermilab Tevatron p¯p collider. We consider a scenario in which the lighter of the two top squarks ˜t1 decays with 100% branching fraction to a charm quark and the lightest neutralino ˜χ⁰ 1 yielding a signal of two acollinear jets with missing transverse energy. We observe 3 events while we expect 3.5 α 1.2 events from the known standard model processes. We exclude at the 95% confidence level a significant region of the mt1 - mχ1 ⁰ parameter space. The highest mt1 value we exclude is 93GeV/c² with a corresponding mχ1 ⁰ value of 8GeV/c². © 1996 The American Physical Society.

Abstract:

We have searched for associated production of the lightest chargino ¯W1 and next-to-lightest neutralino ¯Z2 of the minimal supersymmetric standard model in p¯p collisions at √s=1.8 TeV using the D0 detector at the Fermilab Tevatron collider. Data corresponding to an integrated luminosity of 12.5±0.7pb⁻¹ were examined for events containing three isolated leptons. No evidence for ¯W1¯Z2 pair production was found. Limits on σ(¯W1¯Z2)B(¯W1→ℓν¯Z1)B(¯Z1→ℓℓ¯Z2) are presented. © 1996 The American Physical Society.