Professor Chris Hays

Abstract:

A search for single smuon and single muon sneutrino production in the mSUGRA model with R-parity violation is performed. As such, m1/2 values up to 260 GeV and sneutrino and smuon masses up to 280 GeV are excluded. The exclude domain in the (m0, m1/2) plane extends the region excluded using the dielectron channel.

Abstract:

The R-parity violating decay of the neutralino X̃10 into a moun and two jets in 77.5 pb-1 of data was searched. For tanβ=2, squark masses below 240 GeV/c2 and gluino masses below 224 GeV/c2 were exluded. For equal masses of squarks and gluinos, the mass limit was 265 GeV/c2. These limits were found to be comparable to those achieved previously in complementary channels.

Abstract:

We have measured the W boson mass using the DØ detector and a data sample of 82 pb^-1 from the Fermilab Tevatron collider. This measurement uses W→eν decays, where the electron is close to a boundary of a central electromagnetic calorimeter module. Such "edge" electrons have not been used in any previous DØ analysis, and represent a 14% increase in the W boson sample size. For these electrons, new response and resolution parameters are determined, and revised backgrounds and underlying event energy flow measurements are made. When the current measurement is combined with previous DØ W boson mass measurements, we obtain MW=80.483±0.084 GeV. The 8% improvement from the previous DØ measurement is primarily due to the improved determination of the response parameters for non-edge electrons using the sample of Z bosons with non-edge and edge electrons.