5,736 research outputs found

    Event-by-event analysis of ultra-relativistic heavy-ion collisions in smoothed particle hydrodynamics

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    The method of smoothed particle hydrodynamics (SPH) is applied for ultra-relativistic heavy-ion collisions. The SPH method has several advantages in studying event-by-event fluctuations, which attract much attention in looking for quark gluon plasma (QGP) formation, because it gives a rather simple scheme for solving hydrodynamical equations. Using initial conditions for Au+Au collisions at RHIC energy produced by NeXus event generator, we solve the hydrodynamical equation in event-by-event basis and study the fluctuations of hadronic observables such as dN/dy due to the initial conditions. In particular, fluctuations of elliptic flow coefficient v2 is investigated for both the cases, with and without QGP formation. This can be used as an additional test of QGP formation.Comment: LaTeX, 16 figures, 3 tables, 23 pages. Talk presented at 6th International Workshop on Relativistic Aspects of Nuclear Physics(RANP2000), Caraguatatuba, Tabatinga Beach, Sao Paulo, Brazil, October 17-20, 2000. To be published in the proceedings (World Scientific, Singapore

    Event-by-event fluctuations in hydrodynamical description of heavy-ion collisions

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    Effects caused by the event-by-event fluctuation of the initial conditions in hydrodynamical description of high-energy heavy-ion collisions are investigated. Non-negligible effects appear for several observable quantities, even for a fixed impact parameter b⃗\vec b . They are sensitive to the equation of state, being the dispersions of the observable quantities in general smaller when the QGP phase appears at the beginning of hydrodynamic evolution than when the fluid remains hadron gas during whole the evolution.Comment: 4 pages, 4 figures, talk presented to Quark Matter 2001 Conferenc

    Kondo effect in transport through molecules adsorbed on metal surfaces: from Fano dips to Kondo peaks

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    The Kondo effect observed in recent STM experiments on transport through CoPc and TBrPP-Co molecules adsorbed on Au(111) and Cu(111) surfaces, respectively, is discussed within the framework of a simple model (Phys. Rev. Lett. {\bf 97}, 076806 (2006)). It is shown that, in the Kondo regime and by varying the adequate model parameters, it is possible to produce a crossover from a conductance Kondo peak (CoPc) to a conductance Fano dip (TBrPP-Co). In the case of TBrPP-Co/Cu(111) we show that the model reproduces the changes in the shape of the Fano dip, the raising of the Kondo temperature and shifting to higher energies of the dip minimum when the number of nearest neighbors molecules is lowered. These features are in line with experimental observations indicating that our simple model contains the essential physics underlying the transport properties of such complex molecules.Comment: 4 pages, 3 figures, submitted to PR

    Rutherford scattering with radiation damping

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    We study the effect of radiation damping on the classical scattering of charged particles. Using a perturbation method based on the Runge-Lenz vector, we calculate radiative corrections to the Rutherford cross section, and the corresponding energy and angular momentum losses.Comment: Latex, 11 pages, 4 eps figure

    Critical behavior at Mott-Anderson transition: a TMT-DMFT perspective

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    We present a detailed analysis of the critical behavior close to the Mott-Anderson transition. Our findings are based on a combination of numerical and analytical results obtained within the framework of Typical-Medium Theory (TMT-DMFT) - the simplest extension of dynamical mean field theory (DMFT) capable of incorporating Anderson localization effects. By making use of previous scaling studies of Anderson impurity models close to the metal-insulator transition, we solve this problem analytically and reveal the dependence of the critical behavior on the particle-hole symmetry. Our main result is that, for sufficiently strong disorder, the Mott-Anderson transition is characterized by a precisely defined two-fluid behavior, in which only a fraction of the electrons undergo a "site selective" Mott localization; the rest become Anderson-localized quasiparticles.Comment: 4+ pages, 4 figures, v2: minor changes, accepted for publication in Phys. Rev. Let

    Nuclear multifragmentation within the framework of different statistical ensembles

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    The sensitivity of the Statistical Multifragmentation Model to the underlying statistical assumptions is investigated. We concentrate on its micro-canonical, canonical, and isobaric formulations. As far as average values are concerned, our results reveal that all the ensembles make very similar predictions, as long as the relevant macroscopic variables (such as temperature, excitation energy and breakup volume) are the same in all statistical ensembles. It also turns out that the multiplicity dependence of the breakup volume in the micro-canonical version of the model mimics a system at (approximately) constant pressure, at least in the plateau region of the caloric curve. However, in contrast to average values, our results suggest that the distributions of physical observables are quite sensitive to the statistical assumptions. This finding may help deciding which hypothesis corresponds to the best picture for the freeze-out stageComment: 20 pages, 7 figure

    Combinatorial Hopf algebra of superclass functions of type DD

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    We provide a Hopf algebra structure on the space of superclass functions on the unipotent upper triangular group of type D over a finite field based on a supercharacter theory constructed by Andr\'e and Neto. Also, we make further comments with respect to types B and C. Type A was explores by M. Aguiar et. al (2010), thus this paper is a contribution to understand combinatorially the supercharacter theory of the other classical Lie types.Comment: Last section modified. Recent development added and correction with respect to previous version state