Heavy ion results from CMS

Two- and multi-particle angular correlations in pp, pPb and PbPb collisions at the LHC energies are presented as a function of centrality, charged-particle multiplicity and transverse momentum ($p_{T}$). The data were collected using the CMS detector. The Fourier coefficents in PbPb collisions are measured over an extended $p_{T}$ range up to 100 GeV/c. These $v_{n}$ measurements at high-$p_{T}$ are complementary to the $R_{AA}$ measurements. The elliptic flow of charged and strange particles and the triangular flow of charged particles in pp collisions is measured using the two-particle correlations. A clear mass ordering effect is observed for low-$p_{T}$ $v_{2}$ values. For the first time, in 13 TeV pp collisions, the $v_{2}$ is extracted from four- and six-particle correlations, and is comparable to the $v_{2}$ from two-particle correlations. This supports the collective nature of the long-range correlations in high-multiplicity pp collisions. A Principle Component Analysis (PCA) of two-particle correlations as a function of $p_{T}$ is studied in PbPb collisions at 2.76 TeV and high-multiplicity pPb collisions at 5.02 TeV. The factorization breaking of two-particle correlations can be attributed to the effect of initial-state fluctuations (ISF). Using a PCA approach, Fourier harmonics $V_{n\Delta}$ are characterized through the leading and sub-leading mode terms. The leading modes are essentially equivalent to the two-particle $v_{n}$ harmonics. The sub-leading modes represent the largest sources of factorization breaking. In the context of hydrodynamic models, they are a direct consequence of the ISF.