First measurements of the azimuthal anisotropy of neutral pions produced in PbPb collisions at a center-of-mass energy of sqrt(s(NN)) = 2.76 TeV are presented. The amplitudes of the second Fourier component (v2) of the neutral pion 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 classes of collision centrality in the kinematic range 1.6 pt 8.0 GeV, within the pseudorapidity interval abs(eta) 0.8. The CMS measurements of v2(pt) are similar to previously reported neutral pion azimuthal anisotropy results from sqrt(s(NN)) = 200 GeV AuAu collisions at RHIC, despite a factor of about 14 increase in the center-of-mass energy. In the momentum range 2.5 pt 5.0 GeV, the neutral pion anisotropies are found to be smaller than those observed by CMS for inclusive charged particles.
Chatrchyan et al. (Tue,) studied this question.