First ALICE results from heavy-ion collisions at the LHC

The ALICE detector recorded Pb-Pb collisions at sqrtsNN = 2.76 TeV at the LHC in November-December 2010. We present the results of the measurements that provide a first characterization of the hot and dense state of strongly-interacting matter produced in heavy-ion collisions at these energies. In particular, we describe the measurements of the particle multiplicity, collective flow, Bose-Einstein correlations, high-momentum suppression, and their dependence on the collision centrality. These observables are related to the energy density, the size, the viscosity, and the opacity of the system. Finally, we give an outlook on the upcoming results, with emphasis on heavy flavour production.Comment: 9 pages, 6 figures, proceedings of the "Rencontres de physique de la Vallee d'Aoste", La Thuile, March 201

Results from NA57

The NA57 experiment has measured the production of strange and multi-strange hadrons in heavy-ion collisions at the CERN SPS. After briefly introducing the NA57 apparatus and analysis procedures, we present recent results on strangeness enhancement in Pb-Pb relative to p-Be collisions, on the study of the m_T distributions of strange particles, and on central-to-peripheral nuclear modification factors in Pb-Pb collisions at top SPS energy.Comment: 8 pages, 5 figures, proceeding of plenary talk at Quark Matter 200

Perspectives for the study of charm in-medium quenching at the LHC with ALICE

Charm mesons produced in nucleus-nucleus collisions are expected to be less attenuated (quenched) by the medium than hadrons containing only light quarks, since radiative energy loss of heavy quarks should be reduced by the `dead-cone' effect. We start from a published energy-loss model to derive the quenching for D mesons at the LHC, introducing an approximation of the dead-cone effect and employing a Glauber-based description of the geometry of central Pb-Pb collisions to estimate the in-medium path lengths of c quarks. We show that the exclusive reconstruction of D^0 \to K\pi decays in ALICE allows to measure the nuclear modification factor of the D mesons transverse momentum distribution and the D/(charged hadrons) ratio and, thus, to investigate the energy loss of c quarks.Comment: 10 pages, 9 figures, replaced with published versio

Heavy ions and parton saturation from RHIC to LHC

The phenomenology of gluon saturation at small parton momentum fraction, Bjorken-x, in the proton and in the nucleus is introduced. The experimentally-accessible kinematic domains at the nucleus-nucleus colliders RHIC and LHC are discussed. Finally, the saturation hints emerging from measurements at RHIC and the perspectives for LHC are described.Comment: 6 pages, 4 figures, prepared for the proceedings of ISMD 0

Probing the QGP with charm at ALICE-LHC

The exclusive reconstruction of D^0 mesons in the ALICE experiment allows to study the QCD energy loss of charm quarks in the deconfined quark-gluon plasma (QGP) medium expected to be produced in central nucleus-nucleus collisions at the Large Hadron Collider.Comment: 12 pages, 5 figures, to appear in the proceedings of the International School of Subnuclear Physics (Erice, 2003

Charm production and energy loss at the LHC with ALICE

The latest results on the ALICE performance for production and in-medium QCD energy loss measurements of charm particles at the LHC are presented.Comment: 8 pages, 3 figures, prepared for the proceedings of the "Physics at LHC" conference, Vienna, 13-17 July 200

Heavy flavour in ALICE

The ALICE experiment, currently in the commissioning phase, will study nucleus-nucleus and proton-proton collisions at the CERN Large Hadron Collider (LHC). We review the ALICE heavy-flavour physics program.Comment: 4 pages, 1 figure, prepared for the proceedings of the DIS2008 conference, London, April 200

Suppression of high-pT heavy-flavour particles in Pb-Pb collisions at the LHC, measured with the ALICE detector

The ALICE experiment studies nucleus-nucleus collisions at the LHC in order to investigate the properties of QCD matter at extreme energy densities. The measurement of open charm and open beauty production allows one to probe the mechanisms of heavy-quark propagation, energy loss and hadronization in the hot and dense medium formed in high-energy nucleus-nucleus collisions. In particular, in-medium energy loss is predicted to be different for massless partons (light quarks and gluons) and heavy quarks at moderate momentum. The ALICE apparatus allows us to measure open heavy-flavour particles in several decay channels and with a wide phase-space coverage. We present the results on the nuclear modification factors for heavy-flavour particle production in Pb-Pb collisions at sqrtsNN=2.76 TeV. Using proton-proton and lead-lead collision samples at sqrts=2.76 and 7 TeV and at sqrtsNN=2.76 TeV, respectively, nuclear modification factors R_AA(pT) were measured for D mesons at central rapidity (via displaced decay vertex reconstruction), and for electrons and muons from heavy-flavour decays, at central and forward rapidity, respectively. A large suppression is observed, by a factor 2.5-4 in central Pb--Pb collisions with respect to the pp reference, in the high-pT region, indicating a strong in-medium energy loss of heavy quarks.Comment: 6 pages, 3 figures, proceedings of ICHEP2012, Melbourne, July 201

Charm and beauty production at LHC

This note will be part of Chapter 6.5 of the ALICE Physics Performance Report (PPR), "ALICE Physics: Charm and Beauty", where the capabilities of ALICE for the detection of open heavy flavour particles will be described. We define here the present ALICE baseline for what concerns the heavy flavour production cross sections at LHC and the kinematical distributions of the heavy quark pairs. We start by qualitatively assessing the Bjorken x regimes accessible with charm and beauty measurements at LHC with ALICE (Section 1). In Section 2 we report the most recent results (and the uncertainties) of the next-to-leading order (NLO) pQCD calculations for the cross sections in pp collisions at LHC energies. These results are extrapolated to Pb-Pb collisions in Section 3.1 and to p-Pb collisions in Section 3.2, taking into account nuclear shadowing and parton intrinsic transverse momentum broadening.Heavy quark kinematics as given by the NLO pQCD calculation are reported in Section 4. We tuned the PYTHIA event generator in order to reproduce such results for what concerns the c and b quarks transverse momentum distributions (Section 5). Finally, we report the yields and transverse momentum distributions for D and B mesons (Section 6).Comment: ALICE Collaboration Note, 24 pages, 18 figure

Preparation for heavy-flavour measurements with ALICE at the LHC

ALICE will study nucleus-nucleus and proton-proton collisions at the LHC. The main goal of the experiment is to investigate the properties of QCD matter at the extreme energy densities that will be reached in Pb-Pb collisions. Heavy quarks (charm and beauty) are regarded as powerful tools for this study. After briefly reviewing the ALICE heavy-flavour program, we will describe the preparation for the first measurements to be performed with pp collisions.Comment: 4 pages, 2 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse