No Arabic abstract
Within the first two years of the LHC operation ALICE addressed the major soft physics observables in Pb-Pb and pp collisions. In this contribution we present a selection of these results, with the emphasis on the bulk particle production and on particle correlations. The latter subject is discussed in detail in several dedicated ALICE talks in the same workshop; the reader is referred to the corresponding contributions.
The physics programme of the ALICE experiment at CERN-LHC comprises besides studies of high-energy heavy-ion collisions measurements of proton-proton interactions at unprecedented energies, too. This paper focuses on the global event characterisation in terms of the multiplicity distribution of charged hadrons and mean transverse momentum. These bulk observables become accessible because the detector features excellent track reconstruction, especially at low transverse momenta. The measurement of strange hadrons is of particular interest since the strange-particle phase-space was found to be suppressed beyond canonical reduction at lower center-of-mass energies and the production mechanism of soft particles is not yet fully understood. Here we benefit in particular from particle identification down to very low transverse momentum, i.e. 100 - 300 MeV/c, giving access to spectra and integrated yields of identified hadrons. Equipped with these features, ALICE will play a complementary role w.r.t. other LHC experiments. New interest in the soft part of pp collisions arose recently and new insights in the physics of the underlying event are expected from both, theory and experiment.
The ALICE experiment has several unique features which makes it an important contributor to proton-proton physics at the LHC, in addition to its specific design goal of studying the physics of strongly interacting matter in heavy-ion collisions. The unique capabilities include its low transverse momentum (pT) acceptance, excellent vertexing, particle identification over a broad pT range and jet reconstruction. In this report, a brief review of ALICE capabilities is given for studying bulk properties of produced particles which characterize the underlying events, and the physics of heavy-flavour, quarkonia, photons, di-leptons and jets.
The Large Hadron Collider (LHC), where lead nuclei will collide at the unprecedented c.m.s. energy of 5.5 TeV per nucleon-nucleon pair, will offer new and unique opportunities for the study of the properties of strongly interacting matter at high energy density over extended volumes. We will briefly explain why heavy-flavour particles are well-suited tools for such a study and we will describe how the ALICE experiment is preparing to make use of these tools.
Recent soft physics results from collisions of ultra-relativistic nuclei at Relativistic Heavy Ion Collider (RHIC) operating at Brookhaven National Laboratory (BNL) are reviewed. Topics discussed cover the Beam Energy Scan program with some emphasis on anisotropic particle flow.
ALICE is the dedicated heavy-ion experiment at the Large Hadron Collider. The experiment has also a broad program of QCD measurements in proton-proton (pp) collisions, which have two-fold interest: the study of particle production at the highest energy frontier, and the definition of references for the corresponding measurements in the upcoming Pb-Pb run. We present the first results on the pseudorapidity and transverse-momentum dependence of charged particle production in pp collisions at LHC energies, on the anti-p/p ratio and on the Bose-Einstein particle correlations. As an outlook, we report on the status of the ongoing analyses for strangeness and heavy-flavour production measurements.