Flow and Correlations in Pb–Pb Collisions at sNN=2.76 TeV with the ATLAS Detector at the LHC
Nuclear Physics A
Introduction 1 A list of members of the ATLAS Collaboration and acknowledgements can be found at the end of this issue. The hot and dense medium created in Pb-Pb collisions at the LHC is now under detail theoretical and experimental studies. A particularly useful observable for understanding the properties of this medium is the azimuthal anisotropy of produced particles which became one of the main signatures of the strongly coupled Quark-Gluon Plasma (sQGP) observed at the RHIC and LHC
... HIC and LHC energies. It is expected that the observed azimuthal anisotropy is sensitive to conditions at the very early stage of evolution and it is correlated with the shape of the initial interaction region of colliding nuclei. The initial spatial asymmetry leads to asymmetric pressure gradients in the QGP, which result in a significant azimuthal anisotropy in particle emission, usually expanded into a Fourier series dN Recent measurements from the ATLAS experiment of the azimuthal anisotropy of charged hadron production in the relativistic Pb-Pb collisions at the Large Hadron Collider (LHC) are presented. The results on the integrated and differential flow harmonics were obtained using a variety of approaches, e.g. the event plane, two-particle correlations, two-and four-particle cumulant methods, over a wide range of centrality (0-80)%, pseudorapidity (|η| <2.5) and transverse momentum of 0.03-20 GeV and 45-210 GeV for charged particles and jets respectively. These detailed measurements at low-and high-p T provide new insights into the hydrodynamic picture of the Quark-Gluon Plasma and probe the path-length dependence of partonic energy loss in the dense medium. Fluctuations in the geometry of the initial interaction region are studied by the measurement of event-by-event v 2 − v 4 harmonics, as well as by flow harmonics from the cumulant method. Additional information on initial geometry fluctuations is provided by measurement of the dipolar flow (v 1 ), as well as by the correlations of two and three reaction plane angles of different orders harmonics. Abstract The H. Niewodniczański Adam Trzupek, (on behalf of the ATLAS Collaboration) 1 s NN = 2.76 TeV with the ATLAS Detector at the LHC Flow and Correlations in Pb-Pb Collisions at √ Available online at www.sciencedirect.com Nuclear Physics A 904-905 (2013) 106c-113c 0375-9474/ © 2013 CERN Published by Elsevier B.V. www.elsevier.com/locate/nuclphysa http://dx.