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

D-instantons and multiparticle production in N=4 SYM

N=4 Super-symmetric Yang-Mills theory (N=4 SYM) in the strong coupling regime has been successfully applied (through the AdS/CFT correspondence) to the description of strongly coupled plasma which is a multiparticle state. Yet, the high-energy scattering in the strong coupling limit of N=4 SYM is purely elastic, so this multiparticle final state can never be produced: this is because in this limit the theory is dual to weak supergravity, and the dominant interaction is the elastic graviton exchange. Here we propose a resolution of this dilemma by considering the contribution of D-instantons in $AdS_5$ bulk space to the scattering amplitude. We argue that D-instantons coupled to dilatons and axions are responsible for multiparticle production in strongly coupled N=4 SYM, and the corresponding cross section increases with energy. We evaluate the intercept and the slope of the corresponding Pomeron trajectory in terms of the typical size of the D-instanton, and argue that the resulting physical picture may resemble the real world.Comment: 22 pp and 11 figures in the eps forma

Hadron multiplicity in pp and AA collisions at LHC from the Color Glass Condensate

We provide quantitative predictions for the rapidity, centrality and energy dependencies of inclusive charged-hadron productions for the forthcoming LHC measurements in nucleus-nucleus collisions based on the idea of gluon saturation in the color-glass condensate framework. Our formulation gives very good descriptions of the first data from the LHC for the inclusive charged-hadron production in proton-proton collisions, the deep inelastic scattering at HERA at small Bjorken-x, and the hadron multiplicities in nucleus-nucleus collisions at RHIC.Comment: 7 pages, 8 figures; v3: minor changes, one reference added, results unchanged, the version to appear in Phys. Rev.

Coulomb gap in the one-particle density of states in three-dimensional systems with localized electrons

The one-particle density of states (1P-DOS) in a system with localized electron states vanishes at the Fermi level due to the Coulomb interaction between electrons. Derivation of the Coulomb gap uses stability criteria of the ground state. The simplest criterion is based on the excitonic interaction of an electron and a hole and leads to a quadratic 1P-DOS in the three-dimensional (3D) case. In 3D, higher stability criteria, including two or more electrons, were predicted to exponentially deplete the 1P-DOS at energies close enough to the Fermi level. In this paper we show that there is a range of intermediate energies where this depletion is strongly compensated by the excitonic interaction between single-particle excitations, so that the crossover from quadratic to exponential behavior of the 1P-DOS is retarded. This is one of the reasons why such exponential depletion was never seen in computer simulations.Comment: 6 pages, 1 figur

Production of q bar-q Pairs in Proton-Nucleus Collisions at High Energies

We calculate production of quark-antiquark pairs in high energy proton-nucleus collisions both in the quasi-classical approximation of McLerran-Venugopalan model and including quantum small-$x$ evolution. The resulting production cross section is explicitly expressed in terms of Glauber-Mueller multiple rescatterings in the classical case and in terms of dipole-nucleus scattering amplitude in the quantum evolution case. We generalize the result of one of us (K.T.) beyond the aligned jet configurations. We expand on the earlier results of Blaizot, Gelis and Venugopalan by deriving quark production cross section including quantum evolution corrections in rapidity intervals both between the quarks and the target and between the quarks and the projectile.Comment: 18 pages, 3 figures; typos corrected, discussion extende

Inelastic final-state interaction

The final-state interaction in multichannel decay processes is sytematically studied with application to B decay in mind. Since the final-state inteaction is intrinsically interwoven with the decay interaction in this case, no simple phase theorem like "Watson's theorem" holds for experimentally observed final states. We first examine in detail the two-channel problem as a toy-model to clarify the issues and to remedy common mistakes made in earlier literature. Realistic multichannel problems are too challenging for quantitative analysis. To cope with mathematical complexity, we introduce a method of approximation that is applicable to the case where one prominant inelastic channel dominates over all others. We illustrate this approximation method in the amplitude of the decay B to pi K fed by the intermediate states of a charmed meson pair. Even with our approximation we need more accurate information of strong interactions than we have now. Nonethless we are able to obtain some insight in the issue and draw useful conclusions on general fearyres on the strong phases.Comment: The published version. One figure correcte

Context-Aware Conversational Agents Using POMDPs and Agenda-Based Simulation

Proceedings of: Workshop on User-Centric Technologies and Applications (CONTEXTS 2011), Salamanca, April 6-8, 2011Context-aware systems in combination with mobile devices offer new opportunities in the areas of knowledge representation, natural language processing and intelligent information retrieval. Our vision is that natural spoken conversation with these devices can eventually become the preferred mode for managing their services by means of conversational agents. In this paper, we describe the application of POMDPs and agenda-based user simulation to learn optimal dialog policies for the dialog manager in a conversational agent. We have applied this approach to develop a statistical dialog manager for a conversational agent which acts as a voice logbook to collect home monitored data from patients suffering from diabetes.Funded by projects CICYT TIN2008-06742-C02-02/TSI, CICYT TEC2008-06732-C02-02/TEC, CAM CONTEXTS (S2009/TIC-1485), and DPS2008-07029-C02-02.Publicad

Quantum motion in superposition of Aharonov-Bohm with some additional electromagnetic fields

The structure of additional electromagnetic fields to the Aharonov-Bohm field, for which the Schr\"odinger, Klein-Gordon, and Dirac equations can be solved exactly are described and the corresponding exact solutions are found. It is demonstrated that aside from the known cases (a constant and uniform magnetic field that is parallel to the Aharonov-Bohm solenoid, a static spherically symmetrical electric field, and the field of a magnetic monopole), there are broad classes of additional fields. Among these new additional fields we have physically interesting electric fields acting during a finite time, or localized in a restricted region of space. There are additional time-dependent uniform and isotropic electric fields that allow exact solutions of the Schrodinger equation. In the relativistic case there are additional electric fields propagating along the Aharonov-Bohm solenoid with arbitrary electric pulse shape

DSMC Modeling Of Gasdynamics, Radiation And Fine Particulates In Ionian Volcanic Jets

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