Measurement of the centrality dependence of J/Ψ yields and observation of Z production in lead-lead collisions with the ATLAS detector at the LHC
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 697:4 (2011) 294-312
Abstract:
Using the ATLAS detector, a centrality-dependent suppression has been observed in the yield of J/Ψ mesons produced in the collisions of lead ions at the Large Hadron Collider. In a sample of minimum-bias lead-lead collisions at a nucleon-nucleon centre of mass energy sNN=2.76 TeV, corresponding to an integrated luminosity of about 6.7 μb-1, J/Ψ mesons are reconstructed via their decays to μ+μ- pairs. The measured J/Ψ yield, normalized to the number of binary nucleon-nucleon collisions, is found to significantly decrease from peripheral to central collisions. The centrality dependence is found to be qualitatively similar to the trends observed at previous, lower energy experiments. The same sample is used to reconstruct Z bosons in the μ+μ- final state, and a total of 38 candidates are selected in the mass window of 66 to 116 GeV. The relative Z yields as a function of centrality are also presented, although no conclusion can be inferred about their scaling with the number of binary collisions, because of limited statistics. This analysis provides the first results on J/Ψ and Z production in lead-lead collisions at the LHC. © 2011 CERN.Measurement of the inclusive Φ cross-section in pp collisions at s=7 TeV
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 703:3 (2011) 267-273
Abstract:
The cross-section for inclusive Φ meson production in pp collisions at a centre-of-mass energy of s=7 TeV has been measured with the LHCb detector at the Large Hadron Collider. The differential cross-section is measured as a function of the Φ transverse momentum pT and rapidity y in the region 0.6Measurement of the jet fragmentation function and transverse profile in proton-proton collisions at a center-of-mass energy of 7 TeV with the ATLAS detector
European Physical Journal C 71:12 (2011) 1-27
Abstract:
© (publication year), (publisher). All rights reserved. The jet fragmentation function and transverse profile for jets with 25 GeV < pTjet < 500 GeV and |ηjet| < 1.2 produced in proton-proton collisions with a center-of-mass energy of 7 TeV are presented. The measurement is performed using data with an integrated luminosity of 36 pb−1. Jets are reconstructed and their momentum measured using calorimetric information. The momenta of the charged particle constituents are measured using the tracking system. The distributions corrected for detector effects are compared with various Monte Carlo event generators and generator tunes. Several of these choices show good agreement with the measured fragmentation function. None of these choices reproduce both the transverse profile and fragmentation function over the full kinematic range of the measurement.Measurement of the lepton charge asymmetry in inclusive W production in pp collisions at √s = 7 TeV
Journal of High Energy Physics 2011:4 (2011)
Abstract:
A measurement of the lepton charge asymmetry in inclusive pp → WX production at √s = 7TeV is presented based on data recorded by the CMS detector at the LHC and corresponding to an integrated luminosity of 36 pb -1. This high precision measurement of the lepton charge asymmetry, performed in both the W → eν and W → μν channels, provides new insights into parton distribution functions. Copyright CERN.Measurement of the ratio of the 3-jet to 2-jet cross sections in pp collisions at s=7 TeV
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 702:5 (2011) 336-354