Charm and beauty at the LHC

The Large Hadron Collider at CERN will open a new energy domain for heavy-ion physics. Besides ALICE, the dedicated heavy-ion experiment, also ATLAS and CMS are preparing rich physics programs with nucleus-nucleus collisions. Here we focus on open heavy-flavour and quarkonia studies, among the fields that will most benefit from the high centre-of-mass energy at the LHC. We discuss a few examples of physics issues that can be addressed and we present a selection and comparison (where possible) of results on the expected capability of the three experiments.Comment: 9 pages, 5 figures, Plenary talk at "Hard Probes 2006", Asilomar, CA, 9-16 June 200

Introduction to Low x Physics and Saturation

The idea of saturation of parton densities in small x physics is briefly introduced. Some aspects of saturation are described, mainly focusing on the status of our knowledge on the non-linear equations describing the high parton density regime. Implications of saturation ideas on the description of nuclear collisions at the Relativistic Heavy Ion Collider are discussed.Comment: 8 pages in LaTeX using enclosed appolb.cls, 3 eps figures included using epsfig; minireview at the XXXIIIrd International Symposium on Multiparticle Dynamics (Kracow, Poland, September 5th-11th 2003

Predictions for the heavy-ion programme at the Large Hadron Collider

I review the main predictions for the heavy-ion programme at the Large Hadron Collider (LHC) at CERN, as available in early April 2009. I begin by remembering the standard claims made in view of the experimental data measured at the Super Proton Synchrotron (SPS) at CERN and at the Relativistic Heavy Ion Collider (RHIC) at the BNL. These claims will be used for later discussion of the new opportunities at the LHC. Next I review the generic, qualitative expectations for the LHC. Then I turn to quantitative predictions: First I analyze observables which characterize directly the medium produced in the collisions - bulk observables or soft probes -: multiplicities, collective flow, hadrochemistry at low transverse momentum, correlations and fluctuations. Second, I move to calibrated probes of the medium i.e. typically those whose expectation in the absence of any medium can be described in Quantum Chromodynamics (QCD) using perturbative techniques (pQCD), usually called hard probes. I discuss particle production at large transverse momentum and jets, heavy-quark and quarkonium production, and photons and dileptons. Finally, after a brief review of pA collisions, I end with a summary and a discussion about the potentiality of the measurements at the LHC - particularly those made during the first run - to further substantiate or, on the contrary, disproof the picture of the medium that has arisen from the confrontation between the SPS and RHIC data, and theoretical models.Comment: 64 pages, 40 figures, 7 tables; invited review for "Quark-Gluon Plasma 4"; v2: small changes, some predictions and references added, final versio

Nuclear Structure Functions at Small x in Multiple Scattering Approaches

A simple model for nuclear structure functions in the region of small $x$ and small and moderate $Q^2$, is presented. It is a parameter-free extension, in the Glauber-Gribov approach to nuclear collisions, of a saturation model for the nucleon. A reasonable agreement with experimental data on ratios of nuclear structure functions is obtained. The unintegrated gluon distribution and the behavior of the saturation scale which result from this model are discussed.Comment: LaTeX2e, uses enclosed moriond.sty, 4 pages, 2 eps figures included using epsfig, contribution to the XXXVIIIth Rencontres de Moriond: QCD and Hadronic Interactions, Les Arcs, France, March 22nd-29th 200

A simple model for nuclear structure functions at small xx in the dipole picture

A simple model for nuclear structure functions in the region of small x and small and moderate $Q^2$, is presented. It is a parameter-free extension, in the Glauber-Gribov approach to nuclear collisions, of a saturation model for the nucleon. A reasonable agreement with experimental data on ratios of nuclear structure functions is obtained. Nuclear effects in the longitudinal-to-transverse cross section ratios are found to be small. Predictions of the model for values of $x$ smaller than those available to present experiments are given. The unintegrated gluon distribution and the behaviour of the saturation scale which result from this model are shown and discussed.Comment: LaTeX, 27 pages, 9 postscript figures included using epsfig; final version: discussion on geometrical scaling clarified, comparison of gluon densities with other approaches added, Fig. 8 redone, references added and updated, some misprints corrected, results and conclusions unchange

Jet quenching

Jet quenching studies play a prominent role in our current understanding of ultra-relativistic heavy ion collisions. In this review I first present the available formalism to compute medium-induced gluon radiation. Then I discuss its effect on single particle spectra, with dedicated attention to the case of the radiating parton being a massive quark. Next I examine more differential observables like jet shapes and multiplicities, and the consequences of flow on radiative energy loss. I conclude with some remarks.Comment: LaTeX, 8 pages, 7 eps figures, uses enclosed cjpsuppl.cls; invited talk at Physics at LHC, Vienna, Austria, July 13th-17th 200

Heavy-to-light ratios as a test of medium-induced energy loss at RHIC and the LHC

The ratio of nuclear modification factors of high-$p_T$ heavy-flavored mesons tolight-flavored hadrons (heavy-to-light ratio) is shown to be a sensitive tool to test medium-induced energy loss at RHIC and LHC energies. Heavy-to-light ratios of $D$ mesons at RHIC in the region $7<p_T<12$ GeV, and of $D$ and $B$ mesons at the LHC in the region $10<p_T<20$ GeV, are proposed for such a test. Finally, the different contributions to the nuclear modification factor for electrons at RHIC are analyzed. Preliminary PHENIX and STAR data are compatible with radiative energy loss provided the contribution of electrons from beauty decays is small compared to that from charm.Comment: 5 pages, latex, 4 eps figs included using graphicx; to appear in the proceedings of 18th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions: Quark Matter 2005 (QM 2005), Budapest, Hungary, 4-9 Aug 200

Monte Carlo for Jet Showers in the Medium

The most commonly employed formalisms of radiative energy loss have been derived in the high- energy approximation. In its present form, it is reliable only for the medium modifications of inclusive particle spectra. Modifications to this formalism are expected to be important for less inclusive measurements. This is especially relevant for reconstructed jets in heavy-ion collisions, which are becoming available only recently. We present some ideas to overcome this limitation. Specifically, we show an implementation of radiative energy loss within a jet parton shower. This implementation has been done within the PYTHIA Monte Carlo event generator. We present the publicly available routine Q-PYTHIA and discuss some of the obtained physics results.Comment: 4 pages, 1 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee. Final version with minor typos correcte

Study of D-mesons using hadronic decay channels with the ALICE detector

At LHC energy, heavy quarks will be abundantly produced and the design of the ALICE Experiment will allow us to study their production using several channels. We investigate the feasibility of the study of D mesons reconstructed in their exclusive hadronic decay channel. After reviewing the ALICE potential for such studies, we will present some results for the two more promising decay channels i.e D0->KPi and D+ -> K-Pi+Pi+ obtained with 7 TeV pp data and 5.5 A TeV Pb-Pb Monte Carlo data .Comment: 4 Pages, 5 Figures. Conference Proceeding to be published in Nuclear Physics