No Arabic abstract
Angular correlations are a sensitive probe of the transport properties of the system produced in nucleus-nucleus collisions. Similar studies performed in p-Pb collisions have recently revealed intriguing features as well. In this article, we review the latest results on charged and identified particle correlations obtained with the ALICE detector at the LHC in both Pb-Pb and p-Pb events.
The discovery of correlations between particles separated by several units of pseudorapidity in high-multiplicity pp and p-Pb collisions, reminiscent of structures observed in Pb-Pb collisions, was a challenge to traditional ideas about collectivity in heavy ion collisions. In order to further explore long-range correlations and provide information to theoretical models, correlations between forward trigger muons and mid-rapidity associated hadrons were measured in p-Pb collisions at $sqrt{s_{mbox{NN}}} = 5.02~mbox{TeV}$. The results demonstrate that the nearside and awayside ridges extend to $Deltaeta sim pm 5$ and that the $v_2$ of muons, obtained from subtracting the correlation functions in high- and low-multiplicity events, is $(16pm6)%$ higher in the Pb-going than in the p-going direction. The results are compared with AMPT simulations.
The ALICE experiment has measured quarkonia production in pp and Pb-Pb collisions at the CERN LHC, in the rapidity ranges |y|<0.9 and 2.5<y<4. Quarkonia are considered to be a sensitive probe of deconfinement, and a detailed differential study of their yields can give important information on the properties of the medium created in heavy-ion collisions. In this paper, we will mainly discuss the centrality dependence of the J/psi nuclear modification factors, as well as their p_T and y dependence in bins of centrality, which will be then compared to theoretical models. Preliminary results on the J/psi elliptic flow and on psi(2S) production will also be shown.
The ALICE experiment at the Large Hadron Collider at CERN is optimized to study the properties of the hot, dense matter created in high energy nuclear collisions in order to improve our understanding of the properties of nuclear matter under extreme conditions. In 2009 the first proton beams were collided at the Large Hadron collider and since then data from proton-proton collisions at $sqrt{s}$ = 0.9, 2.36, 2.76, and 7 TeV have been taken. Results from pp collisions provide significant constraints on models. In particular, results on strange particles indicate that Monte Carlo generators still have considerable difficulty describing strangeness production. In 2010 the first lead nuclei were collided at $sqrt{s_{NN}}$ = 2.76 TeV. Results from Pb+Pb demonstrate suppression of particle production relative to that observed in pp collisions, consistent with expectations based on data available at lower energies.
This short overview includes recent results from the ALICE Collaboration on anisotropic flow of charged and identified particles in sqrt(sNN) = 2.76 TeV Pb-Pb collisions. We also discuss charge dependent and event plane dependent azimuthal correlations that are important in tests of the chiral magnetic effect, as well as understanding the dynamics of the system evolution and hadronization process. Lastly, we present ALICE results obtained with a new technique, the event shape engineering, which allows to perform a physical analysis on events with very large or small flow.
We report recent results of high-pt measurements in Pb--Pb collisions at $sqrt{s_{NN}}=2.76$ TeV by the ALICE experiment and discuss the implications in terms of energy loss of energetic partons in the strongly interaction medium formed in the collisions.