Measurement of charged hadron $v_{2}$ at high $p_{T}$ in PbPb collisions at $\sqrt{s_{NN}}=2.76$TeV with CMS

Measurements of the azimuthal anisotropy of charged hadrons are presented for PbPb collisions at $\sqrt{s_{NN}} = 2.76$ TeV over an extended transverse momentum range. The data were collected with the CMS detector at the LHC. The anisotropy parameter ($v_{2}$) is extracted up to a significantly higher $p_{T}$ region than previous achieved, by correlating charged tracks with respect to the event plane reconstructed using the energy deposited in forward-angle calorimeters. These new data can impose quantitative constraints on the details of in-medium parton energy loss models, particularly the influence of the path length and the shape of the interaction region.