Measurement of the cross-section for b-jets produced in association with a Z boson at root s=7 TeV with the ATLAS detector ATLAS Collaboration

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 root 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 P-T electrons or muons, and at least one b-jet, identified by its displaced vertex, with transverse momentum p(T) > 25 GeV and rapidity vertical bar y vertical bar < 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

Measurements of top-quark pair differential cross-sections in the e mu channel in pp collisions at root s=13 TeV using the ATLAS detector

Funded by SCOAP

Search for supersymmetry in events with large missing transverse momentum, jets, and at least one tau lepton in 20 fb(-1) of root s=8 TeV proton-proton collision data with the ATLAS detector

A search for supersymmetry (SUSY) in events with large missing transverse momentum, jets, at least one hadronically decaying tau lepton and zero or one additional light leptons (electron/muon), has been performed using 20.3fb-1 of proton-proton collision data at s \sqrt{s} = 8 TeV recorded with ATLAS detector at Large Hadron Collider. No excess above Standard Model background expectation is observed in various signal regions and 95% confidence level upper limits on visible cross section for new phenomena are set. results of analysis are interpreted in several SUSY scenarios, significantly extending previous limits obtained in same final states. In framework of minimal gauge-mediated SUSY breaking models, values of SUSY breaking scale Λ below 63 TeV are excluded, independently of tan β. Exclusion limits are also derived for an mSUGRA/CMSSM model, in both R-parity-conserving and R-parity-violating case. A further interpretation is presented in a framework of natural gauge mediation, in which gluino is assumed to be only light coloured sparticle and gluino masses below 1090 GeV are excluded. [Figure not available: see fulltext.