2,353 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
Analysis of Bose-Einstein correlations in e+e- -> W+W- events including final state interactions
Recently DELPHI Collaboration reported new data on Bose-Einstein correlations
(BEC) measured in e+e- -> W^+W^- events. Apparently no enhancement has been
observed. We have analyzed these data including final state interactions (FSI)
of both Coulomb and strong (s-wave) origin and found that there is enhancement
in BEC but it is overshadowed by the FSI which are extremely important for
those events. We have found the following values for the size of the
interaction range beta and the degree of coherence lambda: beta=0.87 +/- 0.31fm
and lambda=1.19 +/- 0.48, respectively.Comment: 7pages, 4 figure
Analyses of multiplicity distributions by means of the Modified Negative Binomial Distribution and its KNO scaling function
We analyze various data of multiplicity distributions by means of the
Modified Negative Binomial Distribution (MNBD) and its KNO scaling function,
since this MNBD explains the oscillating behavior of the cumulant moment
observed in e^+e^- annihilations, h-h collisions and e-p collisions. In the
present analyses, we find that the MNBD(discrete distributions) describes the
data of charged particles in e^+e^- annihilations much better than the Negative
Binomial Distribution (NBD). To investigate stochastic property of the MNBD, we
derive the KNO scaling function from the discrete distribution by using a
straightforward method and the Poisson transform. It is a new KNO function
expressed by the Laguerre polynomials. In analyses of the data by using the KNO
scaling function, we find that the MNBD describes the data better than the
gamma function.Thus, it can be said that the MNBD is one of useful formulas as
well as NBD.Comment: 12 pages, latex, 3 figure
Extended Gaussian ensemble or q-statistics in hadronic production processes?
The extended Gaussian ensemble introduced recently as a generalization of the
canonical ensemble, which allows to treat energy fluctuations present in the
system, is used to analyze the inelasticity distributions in high energy
multiparticle production processes.Comment: Presented at NEXT2005 (News, Expectations and Trends in Statistical
Physics, NEXT-SigmaPhi 3rd International Conference) 13-18 August 2005,
Kolymbari CRETE, minor corrections, to be published in Europ. Phys. J. B
(2006
Electronic Structure of Three-Dimensional Superlattices Subject to Tilted Magnetic Fields
Full quantum-mechanical description of electrons moving in 3D structures with
unidirectional periodic modulation subject to tilted magnetic fields requires
an extensive numerical calculation. To understand magneto-oscillations in such
systems it is in many cases sufficient to use the quasi-classical approach, in
which the zero-magnetic-field Fermi surface is considered as a
magnetic-field-independent rigid body in k-space and periods of oscillations
are related to extremal cross-sections of the Fermi surface cut by planes
perpendicular to the magnetic-field direction. We point out cases where the
quasi-classical treatment fails and propose a simple tight-binding
fully-quantum-mechanical model of the superlattice electronic structure.Comment: 8 pages, 7 figures, RevTex, submitted to Phys. Rev.
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