Dr Elizabeth Gallas

Abstract:

A search for microscopic black holes has been performed in a same-sign dimuon final state using 1.3 fb -1 of proton-proton collision data collected with the ATLAS detector at a centre of mass energy of 7 TeV at the CERN Large Hadron Collider. The data are found to be consistent with the expectation from the Standard Model and the results are used to derive exclusion contours in the context of a low scale gravity model. © 2012 CERN.

Abstract:

A search for the standard model Higgs boson is performed in the diphoton decay channel. The data used correspond to an integrated luminosity of 4.9fb-1 collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of √s=7TeV. In the diphoton mass range 110-150GeV, the largest excess with respect to the background-only hypothesis is observed at 126.5GeV, with a local significance of 2.8 standard deviations. Taking the look-elsewhere effect into account in the range 110-150GeV, this significance becomes 1.5 standard deviations. The standard model Higgs boson is excluded at 95% confidence level in the mass ranges of 113-115GeV and 134.5-136GeV. © 2012 CERN.

Abstract:

A measurement is presented of the cross section for the production of a W boson with one or two jets, of which at least one must be a b-jet, in pp collisions at s=7TeV. Production via top decay is not included in the signal definition. The measurement is based on 35pb -1 of data collected with the ATLAS detector at the LHC. The W+b-jet cross section is defined for jets reconstructed with the anti-k t clustering algorithm with transverse momentum above 25 GeV and rapidity within ±2.1. The b-jets are identified by reconstructing secondary vertices. The fiducial cross section is measured both for the electron and muon decay channel of the W boson and is found to be 10.2±1.9(stat)±2.6(syst)pb for one lepton flavour. The results are compared with next-to-leading order QCD calculations, which predict a cross section smaller than, though consistent with, the measured value. © 2011 CERN.

Abstract:

A measurement of the production cross section of top quark pairs (tt̄) in proton-proton collisions at a center-of-mass energy of 7 TeV recorded with the ATLAS detector at the Large Hadron Collider is reported. Candidate events are selected in the dilepton topology with large missing transverse energy and at least two jets. Using a data sample corresponding to an integrated luminosity of 35pb-1, a tt̄ production cross section σtt̄=177±20(stat.)±14(syst.)±7(lum.)pb is measured for an assumed top quark mass of mt=172.5GeV. A second measurement requiring at least one jet identified as coming from a b quark yields a comparable result, demonstrating that the dilepton final states are consistent with being accompanied by b-quark jets. These measurements are in good agreement with Standard Model predictions. © 2011 CERN.

Abstract:

This Letter describes the measurement of elliptic flow of charged particles in lead-lead collisions at sNN=2.76 TeV using the ATLAS detector at the Large Hadron Collider (LHC). The results are based on an integrated luminosity of approximately 7 μb-1. Elliptic flow is measured over a wide region in pseudorapidity, |η|<2.5, and over a broad range in transverse momentum, 0.5

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