Monika Sharma (Vanderbilt University (US))
The first measurements of the elliptic azimuthal anisotropy of neutral pions, pi0s, produced in 2.76 TeV PbPb collisions will be presented. The results are based on data collected by the CMS experiment during the 2010 LHC running period. The amplitudes of the second Fourier component (v2) of the pi0 azimuthal distributions are extracted using an event-plane technique. The values of v2 are studied as a function of the neutral pion transverse momentum (pT) for different centrality classes in the kinematic range pT = 1.6 - 8 GeV/c, and |eta|<0.8. The CMS measurements of v2(pT) agree with previously reported pi0 azimuthal anisotropy results from 200 GeV AuAu collisions measured by the PHENIX experiment at RHIC, despite a factor of ~14 increase in the center-of-mass energy. A comparison of the CMS measurements of v2(pT) from pi0 mesons and inclusive charged particles reveals a systematic difference in the range of pT = 2.5 ~ 5 GeV/c, with the neutral pion anisotropies being weaker than those observed for inclusive charged particles. This difference indicates a particle-species dependence in the azimuthal anisotropy at the LHC.
Collaboration CMS (CERN)