Azimuthal anisotropy of charged particles at high transverse momenta in Pb-Pb collisions at √s NN=2.76TeV

Chatrchyan S., Khachatryan V., Sirunyan A., Tumasyan A., Adam W., Bergauer T., ...More

Physical Review Letters, vol.109, no.2, 2012 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 109 Issue: 2
  • Publication Date: 2012
  • Doi Number: 10.1103/physrevlett.109.022301
  • Journal Name: Physical Review Letters
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Yıldız Technical University Affiliated: No


The azimuthal anisotropy of charged particles in Pb-Pb collisions at √s NN=2.76TeV is measured with the CMS detector at the LHC over an extended transverse momentum (p T) range up to approximately 60GeV/c. The data cover both the low-p T region associated with hydrodynamic flow phenomena and the high-p T region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v 2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v 2 values are found to first increase with p T, reaching a maximum around p T=3GeV/c, and then to gradually decrease to almost zero, with the decline persisting up to at least p T=40GeV/c over the full centrality range measured. © 2012 CERN. Published by the American Physical Society.