Measurement of ZZ production in pp collisions at √ = 7 TeV and limits on anomalous ZZZ and ZZγ couplings with the ATLAS detector
Journal of High Energy Physics 2013:3 (2013)
Abstract:
A measurement of the ZZ production cross section in proton-proton collisions at √ = 7 TeV using data recorded by the ATLAS experiment at the Large Hadron Collider is presented. In a data sample corresponding to an integrated luminosity of 4.6 fb-1 collected in 2011, events are selected that are consistent either with two Z bosons decaying to electrons or muons or with one Z boson decaying to electrons or muons and a second Z boson decaying to neutrinos. The ZZ → ℓ + ℓ - ℓ ′+ ℓ ′- and ZZ → ℓ + ℓ - ℓv̄v cross sections are measured in restricted phase-space regions. These results are then used to derive the total cross section for ZZ events produced with both Z bosons in the mass range 66 to 116 GeV, σZZtot = 6.7 ± 0.7 (stat.) -0.3+0.4 (stat.) ± 0.3 (lumi.) pb, which is consistent with the Standard Model prediction of 5.89-0.18+0.22 pb calculated at next-to-leading order in QCD. The normalized differential cross sections in bins of various kinematic variables are presented. Finally, the differential event yield as a function of the transverse momentum of the leading Z boson is used to set limits on anomalous neutral triple gauge boson couplings in ZZ production. © 2013 Cern for the benefit of the ATLAS collaboration.A search for high-mass resonances decaying to τ+τ- in pp collisions at √s=7 TeV with the ATLAS detector
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 719:4-5 (2013) 242-260
Abstract:
This Letter presents a search for high-mass resonances decaying into τ+τ- final states using proton-proton collisions at s=7 TeV produced by the Large Hadron Collider. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 4.6 fb-1. No statistically significant excess above the Standard Model expectation is observed; 95% credibility upper limits are set on the cross section times branching fraction of Z' resonances decaying into τ+τ- pairs as a function of the resonance mass. As a result, Z' bosons of the Sequential Standard Model with masses less than 1.40 TeV are excluded at 95% credibility. © 2013 CERN.A search for prompt lepton-jets in pp collisions at √s=7TeV with the ATLAS detector
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 719:4-5 (2013) 299-317
Abstract:
We present a search for a light (mass <2GeV) boson predicted by Hidden Valley supersymmetric models that decays into a final state consisting of collimated muons or electrons, denoted "lepton-jets". The analysis uses 5fb-1 of s=7TeV proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider to search for the following signatures: single lepton-jets with at least four muons; pairs of lepton-jets, each with two or more muons; and pairs of lepton-jets with two or more electrons. This study finds no statistically significant deviation from the Standard Model prediction and places 95% confidence-level exclusion limits on the production cross section times branching ratio of light bosons for several parameter sets of a Hidden Valley model. © 2013 CERN.Measurement of the jet radius and transverse momentum dependence of inclusive jet suppression in lead-lead collisions at √sNN=2.76 TeV with the ATLAS detector
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 719:4-5 (2013) 220-241
Abstract:
Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at √sNN=2.76TeV corresponding to an integrated luminosity of approximately 7 μb-1, ATLAS has measured jets with a calorimeter system over the pseudorapidity interval |η|<2.1 and over the transverse momentum range 38Search for long-lived, heavy particles in final states with a muon and multi-track displaced vertex in proton-proton collisions at √s=7TeV with the ATLAS detector
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 719:4-5 (2013) 280-298