Search for pair production of heavy top-like quarks decaying to a high-pT W boson and a b quark in the lepton plus jets final state at s=7TeV with the ATLAS detector
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 718:4-5 (2013) 1284-1302
Abstract:
A search is presented for production of a heavy up-type quark (t') together with its antiparticle, assuming a significant branching ratio for subsequent decay into a W boson and a b quark. The search is based on 4.7 fb-1 of pp collisions at s=7TeV recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. Data are analyzed in the lepton+jets final state, characterized by a high-transverse-momentum isolated electron or muon, large missing transverse momentum and at least three jets. The analysis strategy relies on the substantial boost of the W bosons in the t't̄' signal when mt'≳400GeV. No significant excess of events above the Standard Model expectation is observed and the result of the search is interpreted in the context of fourth-generation and vector-like quark models. Under the assumption of a branching ratio BR(t'→Wb)=1, a fourth-generation t' quark with mass lower than 656GeV is excluded at 95% confidence level. In addition, in light of the recent discovery of a new boson of mass ~126GeV at the LHC, upper limits are derived in the two-dimensional plane of BR(t'→Wb) versus BR(t'→Ht), where H is the Standard Model Higgs boson, for vector-like quarks of various masses. © 2012 CERN.Search for pair production of heavy top-like quarks decaying to a high-pT W boson and a b quark in the lepton plus jets final state at s=7TeV with the ATLAS detector
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 718:4-5 (2013) 1284-1302
Abstract:
A search is presented for production of a heavy up-type quark (t ' ) together with its antiparticle, assuming a significant branching ratio for subsequent decay into a W boson and a b quark. The search is based on 4.7 fb -1 of pp collisions at s=7TeV recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. Data are analyzed in the lepton+jets final state, characterized by a high-transverse-momentum isolated electron or muon, large missing transverse momentum and at least three jets. The analysis strategy relies on the substantial boost of the W bosons in the t't¯' signal when mt'?400GeV. No significant excess of events above the Standard Model expectation is observed and the result of the search is interpreted in the context of fourth-generation and vector-like quark models. Under the assumption of a branching ratio BR(t ' ?Wb)=1, a fourth-generation t ' quark with mass lower than 656GeV is excluded at 95% confidence level. In addition, in light of the recent discovery of a new boson of mass ~126GeV at the LHC, upper limits are derived in the two-dimensional plane of BR(t ' ?Wb) versus BR(t ' ?Ht), where H is the Standard Model Higgs boson, for vector-like quarks of various masses. © 2012 CERN.Measurement of the top-antitop production cross section in the tau+jets channel in pp collisions at sqrt(s) = 7 TeV
ArXiv 1301.5755 (2013)
Measurement of the azimuthal anisotropy of neutral pions in Pb-Pb collisions at √sNN =2.76 TeV
Physical Review Letters 110:4 (2013)
Abstract:
First measurements of the azimuthal anisotropy of neutral pions produced in Pb-Pb collisions at a center-of-mass energy of √sNN=2.76 TeV are presented. The amplitudes of the second Fourier component (v2) of the π0 azimuthal distributions are extracted using an event-plane technique. The values of v2 are studied as a function of the neutral pion transverse momentum (pT) for different classes of collision centrality in the kinematic range 1.6Search for long-lived, multi-charged particles in pp collisions at sqrt(s)=7 TeV using the ATLAS detector
ArXiv 1301.5272 (2013)