ИСТИНА

The azimuthal anisotropy of charged particle emission in heavy ion collisions is a sensitive probe of the properties and the dynamical evolution of the produced matter. The systematic study of elliptic flow (v2), and higher order harmonics can yield information about the equilibration timescale, the nuclear equation of state and the viscosity in the different stages of the system evolution, as well as the initial state conditions of the heavy ion collisions. Experimentally, it is important to be able to reconstruct the flow using different methods, since they have different sensitivity to non-flow correlations and fluctuations which affect the extracted signal. In CMS, the nuclear reaction plane can be determined independently using several different detector subsystems. The reconstruction of elliptic flow using calorimetry and the tracking system will be presented. Progress towards measuring elliptic flow using cumulant and Lee-Yang zero techniques will also be reported.