Professor Amanda Cooper-Sarkar

Abstract:

The cross section for the production of W bosons with subsequent decay W→τντ is measured with the ATLAS detector at the LHC. The analysis is based on a data sample that was recorded in 2010 at a proton-proton center-of-mass energy of s=7 TeV and corresponds to an integrated luminosity of 34 pb-1. The cross section is measured in a region of high detector acceptance and then extrapolated to the full phase space. The product of the total W production cross section and the W→τντ branching ratio is measured to be σW→τντtot=11.1±0.3(stat)±1.7(syst)±0.4(lumi) nb. © 2011 CERN.

Abstract:

A measurement is presented of the inclusive cross-section for b-jet production in association with a Z boson in pp collisions at a centre-of-mass energy of s=7 TeV. The analysis uses the data sample collected by the ATLAS experiment in 2010, corresponding to an integrated luminosity of approximately 36 pb-1. The event selection requires a Z boson decaying into high pT electrons or muons, and at least one b-jet, identified by its displaced vertex, with transverse momentum pT>25 GeV and rapidity |y|<2.1. After subtraction of background processes, the yield is extracted from the vertex mass distribution of the candidate b-jets. The ratio of this cross-section to the inclusive Z cross-section (the average number of b-jets per Z event) is also measured. Both results are found to be in good agreement with perturbative QCD predictions at next-to-leading order. © 2011 CERN.