Observation of sequential Υ suppression in PbPb collisions
Physical Review Letters 109:22 (2012)
Abstract:
The suppression of the individual Υ(nS) states in PbPb collisions with respect to their yields in pp data has been measured. The PbPb and pp data sets used in the analysis correspond to integrated luminosities of 150μb -1 and 230nb-1, respectively, collected in 2011 by the CMS experiment at the LHC, at a center-of-mass energy per nucleon pair of 2.76TeV. The Υ(nS) yields are measured from the dimuon invariant mass spectra. The suppression of the Υ(nS) yields in PbPb relative to the yields in pp, scaled by the number of nucleon-nucleon collisions, RAA, is measured as a function of the collision centrality. Integrated over centrality, the RAA values are 0.56±0.08(stat)±0.07(syst), 0.12±0.04(stat)±0.02(syst), and lower than 0.10 (at 95% confidence level), for the Υ(1S), Υ(2S), and Υ(3S) states, respectively. The results demonstrate the sequential suppression of the Υ(nS) states in PbPb collisions at LHC energies. © 2012 CERN.Search for exotic resonances decaying into WZ/ZZ in pp collisions at sqrt(s) = 7 TeV
ArXiv 1211.5779 (2012)
Measurement of the b-hadron production cross section using decays to D *+μ -X final states in pp collisions at √s = 7 TeV with the ATLAS detector
Nuclear Physics B 864:3 (2012) 341-381
Abstract:
The b-hadron production cross section is measured with the ATLAS detector in pp collisions at s=7TeV, using 3.3pb -1 of integrated luminosity, collected during the 2010 LHC run. The b-hadrons are selected by partially reconstructing D z.ast;+μ -X final states. Differential cross sections are measured as functions of the transverse momentum and pseudorapidity. The measured production cross section for a b-hadron with p T>9GeV and |n|<2.5 is 32.7±0.8(stat.)-6.8+4.5(syst.)μb, higher than the next-to-leading-order QCD predictions but consistent within the experimental and theoretical uncertainties. © 2012.Measurement of the b-hadron production cross section using decays to D*+μ-X final states in pp collisions at √s = 7 TeV with the ATLAS detector
Nuclear Physics B 864:3 (2012) 341-381