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Paper   IPM / Particles / 12414
School of Particles and Accelerator
  Title:   Study of W boson production in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV
  Author(s): 
1.  Hessamadin Arfaei
2.  Hamed Bakhshiansohi
3.  Seyed Mohsen Etesami
4.  Ali Fahim
5.  Majid Hashemi
6.  Hoda Hesari
7.  Abideh Jafari
8.  Mohsen Khakzad
9.  A Mohammadi
10.  Mojtaba Mohammadi Najafabadi
11.  Saeid Paktinat
12.  Batool Safarzadeh
13.  Maryam Zeinali
  Status:   Published
  Journal: Phys. Lett. B
  Vol.:  715
  Year:  2012
  Pages:   66-87
  Supported by:  IPM
  Abstract:
A measurement is presented of W-boson production in PbPb collisions carried out at a nucleon-nucleon (NN) centre-of-mass energy sqrt(s[NN]) of 2.76 TeV at the LHC using the CMS detector. In data corresponding to an integrated luminosity of 7.3 inverse microbarns, the number of W to mu mu-neutrino decays is extracted in the region of muon pseudorapidity abs(eta[mu])<2.1 and transverse momentum pt[mu]>25 GeV. Yields of muons found per unit of pseudorapidity correspond to (159 +/- 10 (stat.) +/- 12 (syst.)) 10E-8 W(plus) and (154 +/- 10 (stat.) +/- 12 (syst.)) 10E-8 W(minus) bosons per minimum-bias PbPb collision. The dependence of W production on the centrality of PbPb collisions is consistent with a scaling of the yield by the number of incoherent NN collisions. The yield of W bosons is also studied in a sample of pp interactions at sqrt(s)= 2.76 TeV corresponding to an integrated luminosity of 231 inverse nanobarns. The individual W(plus) and W(minus) yields in PbPb and pp collisions are found to agree, once the neutron and proton content in Pb nuclei is taken into account. Likewise, the difference observed in the dependence of the positive and negative muon production on pseudorapidity is consistent with next-to-leading order perturbative QCD calculations

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