Gluon saturation effects on J/Psi production in heavy ion collisions

We consider a novel mechanism for J/Psi production in nuclear collisions arising due to the high density of gluons. We calculate the resulting J/Psi production cross section as a function of rapidity and centrality. We evaluate the nuclear modification factor and show that the rapidity distribution of the produced J/Psi's is significantly more narrow in AA collisions due to the gluon saturation effects. Our results indicate that gluon saturation in the colliding nuclei is a significant source of J/Psi suppression that can be disentangled from the quark-gluon plasma effects.Comment: 5 pages, 3 figures; v2: typos corrected; presentation improve

The role of graphics super-workstations in a supercomputing environment

A new class of very powerful workstations has recently become available which integrate near supercomputer computational performance with very powerful and high quality graphics capability. These graphics super-workstations are expected to play an increasingly important role in providing an enhanced environment for supercomputer users. Their potential uses include: off-loading the supercomputer (by serving as stand-alone processors, by post-processing of the output of supercomputer calculations, and by distributed or shared processing), scientific visualization (understanding of results, communication of results), and by real time interaction with the supercomputer (to steer an iterative computation, to abort a bad run, or to explore and develop new algorithms)

Energy dependence of the survival probability of large rapidity gap

The energy dependence for the survival probability of large rapidity gaps (LRG) $$, is calculated in an Eikonal model assuming a Gaussian opacity. The parameters determining$$ are evaluated directly from experimental data, without further recourse to models. We find that $$ decreases with increasing energy, in line with recent results for LRG dijet production at the Tevatron.Comment: 12 pages of text in latex file, 5 figures in eps file

N=4 SYM and QCD motivated approach to soft interactions at high energies

In this paper we construct a model that satisfies the theoretical requisites of high energy soft interactions, based on two ingredients:(i) the results of N=4 SYM, which at present is a unique theory that allows one to deal with a large coupling constant; and (ii) the requirement of matching with high energy QCD. In accordance with these ideas, we assume that the soft Pomeron intercept is rather large, and the slope of the Pomeron trajectory is equal to zero. We derive analytical formulae that sum both enhanced and semi-enhanced diagrams for elastic and diffractive amplitudes. We fit the available experimental data, and predict the valuefor cross sections at the energies accessible at the LHC. The main corrections to the model are studied and evaluated.Comment: 36 pp. 20 figures and 3 table