Azimuthal anisotropies and initial-state fluctuations from SPS to LHC energies

Abstract

The v3 coefficient, obtained using the PbAu data from the CERES detector at the top SPS energy of √sNN = 17.3 GeV, is presented. The v2 is measured over a pT range up to 100 GeV/c in PbPb collisions collected with the CMS detector. The v2{2} of charged and strange particles emitted in pp collisions shows a mass ordering effect. The v2{4} and v2{6} are comparable to the v2{2}, and thus supports the collective nature of the long-range correlations in high-multiplicity pp collisions at 13 TeV. Principle Component Analysis (PCA) of two-particle harmonics (VnΔ) is studied in PbPb and high-multiplicity pPb collisions at the LHC. The factorization breaking of the VnΔ can be attributed to the effect of initial-state fluctuations. Using a PCA, the VnΔ are characterized through the leading and sub-leading modes. The leading modes are essentially equivalent to the vn{2}. The sub-leading modes represent the largest sources of factorization breaking.