Dr Elizabeth Gallas

Abstract:

The D0 Collaboration has performed a measurement of the top quark mass mt based on six candidate events for the process tt- → bW+bW-, where the W bosons decay to eν or μν. This sample was collected during an exposure of the D0 detector to an integrated luminosity of 125pb-1 of √ s = 1.8 TeV pp collisions. We obtain mt = 168.4 ± 12.3(stat) ± 3.6(syst) GeV/c2, consistent with the measurement obtained using single-lepton events. Combination of the single-lepton and dilepton results yields mt = 172.0 ± 7.5 GeV/c2. © 1998 The American Physical Society.

Abstract:

We have searched for first generation scalar leptoquark (LQ) pairs in the ev + jets channel using pp collider data (∫L dt ≈ 115pb^-1) collected by the D0 experiment at the Fermilab Tevatron during 1992-1996. The analysis yields no candidate events. We combine the results with those from the ee + jets vv + jets channels to obtain 95% confidence level (C.L.) upper limits on the LQ pair production cross section as a function of mass and of β, the branching fraction to a charged lepton. Comparing with the next-to-leading order theory, we set 95% C.L. lower limits on the LQ mass of 225, 204, and 79 GeV/c² for β = 1, 1/2, and 0, respectively. © 1998 The American Physical Society.

Abstract:

We have searched for central production of a pair of photons with high transverse energies in pp̄ collisions at √s=1.8 TeV using 70pb-1 of data collected with the D0 detector at the Fermilab Tevatron in 1994-1996. If they exist virtual heavy pointlike Dirac monopoles could rescatter pairs of nearly real photons into this final state via a box diagram. We observe no excess of events above background and set lower 95% C.L. limits of 610 870 or 1580 GeV/c² on the mass of a spin 0 1/2 or 1 Dirac monopole. © 1998 The American Physical Society.

Abstract:

This report describes the first search for top squark pair production in the channel (Formula presented)+jets+(Formula presented) using (Formula presented) pb(Formula presented) of data collected using the DØ detector. A 95% confidence level upper limit on (Formula presented) is presented. The limit is above the theoretical expectation for (Formula presented) for this process, but does show the sensitivity of the current DØ data set to a particular topology for new physics. © 1998 The American Physical Society.