Search for contact interactions in dilepton events from pp collisions at 鈭歴=7 TeV with the ATLAS detector
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 712:1-2 (2012) 40-58
Abstract:
This Letter presents a search for contact interactions in the dielectron and dimuon channels using data from proton-proton collisions produced by the LHC at s=7 TeV and recorded by the ATLAS detector. The data sample, collected in 2011, corresponds to an integrated luminosity of 1.08 and 1.21 fb-1 in the e+e- and 渭+渭- channels, respectively. No significant deviations from the standard model are observed. Using a Bayesian approach with a prior flat in 1/螞2, the following 95% CL lower limits are placed on the energy scale of 鈩撯創qq contact interactions: 螞->10.1 TeV (螞+>9.4 TeV) in the electron channel and 螞->8.0 TeV (螞+>7.0 TeV) in the muon channel for constructive (destructive) interference in the left-left isoscalar contact interaction model. Limits are also provided for a prior flat in 1/螞4. 漏 2012 CERN.Search for heavy vector-like quarks coupling to light quarks in proton-proton collisions at 鈭歴=7 TeV with the ATLAS detector
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 712:1-2 (2012) 22-39
Abstract:
This Letter presents a search for singly produced vector-like quarks, Q, coupling to light quarks, q. The search is sensitive to both charged current (CC) and neutral current (NC) processes, pp鈫扱q鈫扺qq' and pp鈫扱q鈫抁qq' with a leptonic decay of the vector gauge boson. In 1.04fb-1 of data taken in 2011 by the ATLAS experiment at a center-of-mass energy 鈭歴=7 TeV, no evidence of such heavy vector-like quarks is observed above the expected Standard Model background. Limits on the heavy vector-like quark production cross section times branching ratio as a function of mass mQ are obtained. For a coupling 魏qQ=v/mQ, where v is the Higgs vacuum expectation value, 95% C.L. lower limits on the mass of a vector-like quark are set at 900 GeV and 760 GeV from CC and NC processes, respectively. 漏 2012 CERN.Inclusive-jet photoproduction at HERA and determination of alphas
(2012)
Measurement of the top quark pair production cross-section with ATLAS in the single lepton channel
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 711:3-4 (2012) 244-263
Abstract:
A measurement of the production cross-section for top quark pairs (tt-) in pp collisions at s=7TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in the single lepton topology by requiring an electron or muon, large missing transverse momentum and at least three jets. With a data sample of 35 pb -1, two different multivariate methods, one of which uses b-quark jet identification while the other does not, use kinematic variables to obtain cross-section measurements of 蟽tt-=187卤11(stat.)-17+18(syst.)卤6(lumi.)pb and 蟽tt-=173卤17(stat.)-16+18(syst.)卤6(lumi.)pb respectively. The two measurements are in agreement with each other and with QCD calculations. The first measurement has a better a priori sensitivity and constitutes the main result of this Letter. 漏 2012 CERN.Search for scalar bottom quark pair production with the ATLAS detector in pp collisions at 鈭歴=7TeV
Physical Review Letters 108:18 (2012)