5,955 research outputs found
Event-by-event analysis of ultra-relativistic heavy-ion collisions in smoothed particle hydrodynamics
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
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 . 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
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
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
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
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
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
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