Effects of shadowing on Drell-Yan dilepton production in high energy nuclear collisions

We compute cross sections for the Drell-Yan process in nuclear collisions at next-to-leading order (NLO) in \alpha_s. The effects of shadowing on the normalization and on the mass and rapidity dependence of these cross sections are presented. An estimate of higher order corrections is obtained from next-to-next-to-leading order (NNLO) calculation of the rapidity-integrated mass distribution. Variations in these predictions resulting from choices of parton distribution sets are discussed. Numerical results for mass distributions at NLO are presented for RHIC and LHC energies, using appropriate rapidity intervals. The shadowing factors in the dilepton mass range 2 < M < 10 GeV are predicted to be substantial, typically 0.5 - 0.7 at LHC, 0.7 - 0.9 at RHIC, and approximately independent of the choice of parton distribution sets and the order of calculation.Comment: 13 pages, 9 eps figure

Disparate responses of tumour vessels to angiotensin II: tumour volume-dependent effects on perfusion and oxygenation

Perfusion and oxygenation of experimental tumours were studied during angiotensin II (AT II) administration whereby the rate of the continuous AT II infusion was chosen to increase the mean arterial blood pressure (MABP) by 50–70 mmHg. In subcutaneous DS- sarcomas the red blood cell (RBC) flux was assessed using the laser Doppler technique and the mean tumour oxygen partial pressure (p O 2) was measured polarographically using O 2-sensitive catheter and needle electrodes. Changes in RBC flux with increasing MABP depended mainly on tumour size. In small tumours, RBC flux decreased with rising MABP whereas in larger tumours RBC flux increased parallel to the MABP. As a result of these volume-dependent effects on tumour blood flow, the impact of AT II on tumour p O 2 was also mainly tumour volume-related. In small tumours oxygenation decreased with increasing MABP during AT II infusion, whereas in large tumours a positive relationship between blood pressure and O 2 status was found. This disparate behaviour might be the result of the co-existence of two functionally distinct populations of tumour vessels. In small tumours, perfusion decreases presumably due to vasoconstriction of pre-existing host vessels feeding the tumour. In larger malignancies, newly formed tumour vessels predominate and seem not to have this vasoresponsive capability (lack of smooth muscle cells and/or AT receptors), resulting in an improvement of perfusion which is not tumour-related per se, but is due to the increased perfusion pressure. © 2000 Cancer Research Campaig

Evidence for charmonium generation at the phase boundary in ultra-relativistic nuclear collisions

We investigate the transition from suppression to enhancement of J/psi mesons produced in ultra-relativistic nuclear collisions in the framework of the statistical hadronization model. The calculations are confronted with the most recent data from the RHIC accelerator. This comparison yields first direct evidence for generation of J/psi mesons at the phase boundary. Based on the success of this approach we make specific predictions for LHC energy.Comment: 5 pages, 2 figures; final version accepted for publication in Phys. Lett. B (Fig.1 containd a new set of calculations

B_c Meson Production in Nuclear Collisions at RHIC

We study quantitatively the formation and evolution of B_c bound states in a space-time domain of deconfined quarks and gluons (quark-gluon plasma, QGP). At the Relativistic Heavy Ion Collider (RHIC) one expects for the first time that typical central collisions will result in multiple pairs of heavy (in this case charmed) quarks. This provides a new mechanism for the formation of heavy quarkonia which depends on the properties of the deconfined region. We find typical enhancements of about 500 fold for the B_c production yields over expectations from the elementary coherent hadronic B_c-meson production scenario. The final population of bound states may serve as a probe of the plasma phase parameters.Comment: 9 Pages, 11 Postscript Figure

An Experimental Overview of Results Presented at SQM 2006

I have been asked to give an critical overview on the experimental results shown in the conference with a emphasis of what has been learned and the challenges that are ahead in trying to understand the physics of the strongly interacting quark-gluon plasma. I will not try to summarize all of the results presented, rather I will concentrate primarily on RHIC data from this conference. Throughout this summary, I will periodically review some of the previous results for those not familiar with the present state of the field.Comment: 15 pages, 12 Figure

Statistical hadronization of charm at SPS, RHIC and LHC

We study the production of charmonia and charmed hadrons for nucleus-nucleus collisions at SPS, RHIC, and LHC energies within the framework of the statistical hadronization model. Results from this model are compared to the observed centrality dependence of J/psi production at SPS energy. We further provide predictions for the centrality dependence of the production of open and hidden charm mesons at RHIC and LHC.Comment: Contribution to Quark Matter 2002, 4 pages, 3 figures; revised version including charmed hyperons (omitted in v1

J/ψJ/\psi Gluonic Dissociation Revisited : I. Fugacity, Flux And Formation Time Effects

We revisit the standard treatment [Xu, Kharzeev, Satz and Wang, Phys. Rev. C {\bf 53}, 3051 (1996)] of $J/\psi$ suppression due to gluonic bombardment in an equilibrating quark-gluon plasma. Effects arising from gluon fugacity, relative $g-\psi$ flux, and $\psi$ meson formation time are correctly incorporated in the formulation of the gluon number density, velocity-weighted cross section, and the survival probability. Our new formulae are applied to numerically study the pattern of $J/\psi$ suppression in the central rapidity region at RHIC/LHC energies. The temperature and transverse momentum dependence of our graphs have noticeable differences from those of Xu et al.Comment: 15 pages, 6 figure