Charm and beauty of the Large Hadron Collider

With the acceleration of lead nuclei in the LHC, heavy-ion physics will enter a new energy domain. One of the main novelties introduced by the 30-fold energy-jump from RHIC to the LHC is the abundant heavy-quark production. After discussing a few examples of physics issues that can be addressed using heavy quarks, we present a selection of results on the expected experimental capability of ALICE, the dedicated heavy-ion experiment at the LHC, in the open-heavy-flavour sector.Comment: 10 pages, 5 figures. Invited talk at Strangeness in Quark Matter (SQM) 2004, Cape Town, South Africa, 15-20 September 2004. Submitted to J. Phys.

Charm quenching in heavy-ion collisions at the LHC

D-meson suppression in Pb-Pb collisions at the LHC due to charm quark in-medium energy loss is estimated within a model that describes the available quenching measurements at RHIC. The result is compared to that previously published by the author. The expected sensitivity of the ALICE experiment for studying charm energy loss via fully-reconstructed D^0-meson decays is also presented.Comment: 8 pages, 3 figures. To appear in the proceedings of Hot Quarks 2004: Workshop for Young Scientists on the Physics of Ultrarelativistic Nucleus-Nucleus Collisions, Taos Valley, New Mexico, 18-24 July 2004. Submitted to J. Phys.

ALICE potential for heavy-flavour physics

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.Comment: 6 pages, 3 figures, prepared for the Proceedings of "Strange Quark Matter 2007", Levoca, Slovaki

How sensitive are high-pt electron spectra at RHIC to heavy quark energy loss?

In nucleus-nucleus collisions, high-pt electron spectra depend on the medium modified fragmentation of their massive quark parents, thus giving novel access to the predicted mass hierarchy of parton energy loss. Here we calculate these spectra in a model, which supplements the perturbative QCD factorization formalism with parton energy loss. In general, we find - within large errors - rough agreement between theory and data on the single inclusive electron spectrum in pp, its nuclear modification factor, and its azimuthal anisotropy. However, the nuclear modification factor depends on the relative contribution of charm and bottom production, which we find to be affected by large perturbative uncertainties. In order for electron measurements to provide a significantly more stringent test of the expected mass hierarchy, one must then disentangle the b- and c-decay contributions, for instance by reconstructing the displaced decay vertices.Comment: 9 pages RevTex, 4 eps-figures, asci-file containing numerical tables of results include

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

Measuring beauty production in Pb-Pb collisions at the LHC via single electrons in ALICE

We present the expected ALICE performance for the measurement of the p_t-differential cross section of electrons from beauty decays in central Pb-Pb collisions at the LHC.Comment: 4 pages, 2 figures, proceeding of poster presentation at "Quark Matter 2005

Correlations of Heavy Quarks Produced at Large Hadron Collider

We study the correlations of heavy quarks produced in relativistic heavy ion collisions and find them to be quite sensitive to the effects of the medium and the production mechanisms. In order to put this on a quantitative footing, as a first step, we analyze the azimuthal, transverse momentum, and rapidity correlations of heavy quark-anti quark ($Q\overline{Q}$) pairs in $pp$ collisions at $\cal{O}$($\alpha_{s}^{3}$). This sets the stage for the identification and study of medium modification of similar correlations in relativistic collision of heavy nuclei at the Large Hadron Collider. Next we study the additional production of charm quarks in heavy ion collisions due to multiple scatterings, {\it viz.}, jet-jet collisions, jet-thermal collisions, and thermal interactions. We find that these give rise to azimuthal correlations which are quite different from those arising from prompt initial production at leading order and at next to leading order.Comment: 26 pages, 15 figures. Three new figures added, comparison to experimental data included, abstract and discussion expande

Nuclear collisions at the Future Circular Collider

The Future Circular Collider is a new proposed collider at CERN with centre-of-mass energies around 100 TeV in the pp mode. Ongoing studies aim at assessing its physics potential and technical feasibility. Here we focus on updates in physics opportunities accessible in pA and AA collisions not covered in previous Quark Matter contributions, including Quark-Gluon Plasma and gluon saturation studies, novel hard probes of QCD matter, and photon-induced collisions.Comment: 4 pages, 5 figures, proceedings of Quark Matter 201

D meson nuclear modification factors in Pb-Pb collisions at {\surd}sNN = 2.76 TeV, measured with the ALICE detector

The ALICE experiment has measured the D meson production in pp and Pb-Pb collisions at the LHC at {\surd}s = 7 and 2.76 TeV and {\surd}sNN = 2.76 TeV respectively, via the exclusive reconstruction of hadronic decay channels. The analyses of the D0{\to}K-pi+ and D+{\to}K-pi+pi+ channels will be described and the preliminary results for the D0 and D+ nuclear modification factor will be presented.Comment: Proceedings of Quark Matter 2011 conference. 4 pages, 4 figures. The slides of the talk can be found at the link: http://indico.cern.ch/materialDisplay.py?contribId=591&sessionId=53&materialId=slides&confId=3024

Flow effects on jet profiles and multiplicities

We study the effects of low-$p_T$ collective flow on radiative energy loss from high-$p_T$ partons traversing the QCD medium created in high-energy nucleus-nucleus collisions. We illustrate this idea through three examples. Due to longitudinal flow, jet profiles at the LHC present marked asymmetries in the $\eta\times \phi$-plane, and widths in $\eta$ and $\phi$ of particle distributions associated with a high-$p_T$ trigger at RHIC become different. Finally, transverse flow implies an increase of high-$p_T$ $v_2$ at RHIC.Comment: LaTeX, 4 pages, 4 eps figs included using graphics, uses enclosed svepj.clo and svjour.cls; proceedings of Hard Probes 2004, Ericeira, Portugal, November 4th-10th 200