Classical gluodynamics in curved space--time and the soft Pomeron

QCD at the classical level possesses scale invariance which is broken by quantum effects. This ``dimensional transmutation'' phenomenon can be mathematically described by formulating classical gluodynamics in a curved, conformally flat, space-time with non-vanishing cosmological constant. We study QCD high-energy scattering in this theory. We find that the properties of the scattering amplitude at small momentum transfer are determined by the energy density of vacuum fluctuations. The approach gives rise to the power growth of the total hadron-hadron cross section with energy, i.e. the Pomeron. The intercept of the Pomeron and the multiplicity of produced particles are evaluated. We also speculate about a possible link between conformal anomaly and TeV scale quantum gravity.Comment: 13 pages, 4 figure

Chemical composition of the decaying glasma

The the initial stage of a relativistic heavy ion collision can be described by a classical color field configuration known as the Glasma. The production of quark pairs from this background field is then computed nonperturbatively by numerically solving the Dirac equation in the classical background. The result seems to point towards an early chemical equilibration of the plasma.Comment: 8 pages, 5 figures, invited talk at Stangeness in Quark Matter 2006 (SQM06), UCLA, March 200

Recent Heavy-Flavor results at STAR

We present the recent results on non-photonic electron (NPE) yields from RHIC run8 p+p collisions. The $e/\pi$ ratio as a function of $p_T$ in run8 with a factor of 10 reduction of the inner detector material at STAR is found to be consistent with those results from run3 taking into account the NPE from charm leptonic decay and the difference of photonic electron yield from photon conversion in detector material. \Jpsi spectra in \pp and \cucu collisions at \sNN = 200 GeV with high sampled luminosity \Jpsi spectrum at high-\pT follows $x_T$ scaling, but the scaling is violated at low \pT. $J/\psi$-hadron correlations in \pp collisions are studied to understand the \Jpsi production mechanism at high $p_T$. We observed an absence of charged hadrons accompanying \Jpsi on the near-side, in contrast to the strong correlation peak in the di-hadron correlations. This constrains the $B$-meson contribution and jet fragmentation to inclusive \Jpsi to be ${}^{<}_{\sim}17$. Yields in minimum-bias \cucu collisions are consistent with those in \pp collisions scaled by the underlying binary nucleon-nucleon collisions in the measured \pT range. Other measurements and future projects related to heavy-flavors are discussed.Comment: 8 pages 4 figures, proceedings of the International Conference on Strangeness in Quark Matter 2008 - Beijing, China, Oct. 6-10, 200

Cold nuclear effects on heavy flavours (a review)

Before wondering about the quark-gluon plasma (QGP), one has to take into account various cold (normal) nuclear matter effects, that can be probed through p+A like collisions. This article aims at reviewing the current results (and understanding) of these effects on heavy quarks and quarkonia production.Comment: 8 pages, 6x2 figures, SQM08 proceedings, version accepted by J.Phys.G. Figure 4 left and 5 right remad

Cronin Effect and High-p_T Suppression in pA Collisions

We review the predictions of the theory of Color Glass Condensate for gluon production cross section in p(d)A collisions. We demonstrate that at moderate energies, when the gluon production cross section can be calculated in the framework of McLerran-Venugopalan model, it has only partonic level Cronin effect in it. At higher energies/rapidities corresponding to smaller values of Bjorken x quantum evolution becomes important. The effect of quantum evolution at higher energies/rapidities is to introduce suppression of high-p_T gluons slightly decreasing the Cronin enhancement. At still higher energies/rapidities quantum evolution leads to suppression of produced gluons at all values of p_T.Comment: 32 pages, 8 figures, v2: extended and improved discussion, references adde

Thermal Dileptons at LHC

We predict dilepton invariant-mass spectra for central 5.5 ATeV Pb-Pb collisions at LHC. Hadronic emission in the low-mass region is calculated using in-medium spectral functions of light vector mesons within hadronic many-body theory. In the intermediate-mass region thermal radiation from the Quark-Gluon Plasma, evaluated perturbatively with hard-thermal loop corrections, takes over. An important source over the entire mass range are decays of correlated open-charm hadrons, rendering the nuclear modification of charm and bottom spectra a critical ingredient.Comment: 2 pages, 2 figures, contributed to Workshop on Heavy Ion Collisions at the LHC: Last Call for Predictions, Geneva, Switzerland, 14 May - 8 Jun 2007 v2: acknowledgment include

Heavy-ion collisions at the LHC - Last call for predictions

This writeup is a compilation of the predictions for the forthcoming Heavy Ion Program at the Large Hadron Collider, as presented at the CERN Theory Institute 'Heavy Ion Collisions at the LHC - Last Call for Predictions', held from 14th May to 10th June 2007.This is a manuscript of an article from Journal of Physics G 35 (2008): 054001, doi: 10.1088/0954-3899/35/5/054001. Posted with permission.</p