854 research outputs found

    Initial conditions, equations of state and final state in hydrodynamics

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    In this paper we present properties of relativistic and non-relativistic perfect hydrodynamical models. In particular we show illustrations of the fact that different initial conditions and equations of state can lead to the same hadronic final state. This means that alone from the hadronic observables one cannot determine either of the above, one needs for example penetrating probes that inherit their properties from each timeslice of the evolution of the fireball.Comment: Presented at the IV Workshop on Particle Correlations and Femtoscopy. 6 pages, 3 figure

    Time evolution of the anisotropies of the hydrodynamically expanding sQGP

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    In high energy heavy ion collisions of RHIC and LHC, a strongly interacting quark gluon plasma (sQGP) is created. This medium undergoes a hydrodynamic evolution, before it freezes out to form a hadronic matter. The initial state of the sQGP is determined by the initial distribution of the participating nucleons and their interactions. Due to the finite number of nucleons, the initial distribution fluctuates on an event-by-event basis. The transverse plane anisotropy of the initial state can be translated into a series of anisotropy coefficients or eccentricities: second, third, fourth-order anisotropy etc. These anisotropies then evolve in time, and result in measurable momentum-space anisotropies, to be measured with respect to their respective symmetry planes. In this paper we investigate the time evolution of the anisotropies. With a numerical hydrodynamic code, we analyze how the speed of sound and viscosity influence this evolution.Comment: 10 pages, 6 figures. To appear in the Gribov-85 Memorial Workshop's proceedings volume. Supported by OTKA NK 10143

    Multipole solution of hydrodynamics and higher order harmonics

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    The time evolution of the medium created in heavy ion collisions can be described by hydrodynamical models. After expansion and cooling, the hadrons are created in a freeze-out. Their distribution describes the final state of this medium. In particular their azimuthal asymmetry, characterized by the elliptic flow coefficient v2v_2, is one of the most important observables in heavy ion physics. In recent years it has been revealed that if measuring relative to higher order event planes Ψn\Psi_n, higher order flow coefficients vnv_n for n>2n>2 can be measured. This is due to initial state fluctuations, previously not described by analytic solutions of relativistic hydrodynamics. In this paper we show the first solutions that utilize higher order asymmetries and thus yield realistic vnv_n flow coefficients. It is a clear consequence of this that different flow patterns may lead to the same observed flow coefficients. We also compare our results to PHENIX measurements and determine a possible parameter set corresponding to these data.Comment: 7 pages, 6 figures, accepted in Phys. Rev.

    Dilepton creation based on an analytic hydrodynamic solution

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    High-energy collisions of various nuclei, so called ``Little Bangs'' are observed at various experiments of heavy ion colliders. The time evolution of the strongly interacting quark-gluon plasma created in heavy ion collisions can be described by hydrodynamical models. After expansion and cooling, the hadrons are created in a freeze-out. Their distribution describes the final state of this medium. To investigate the time evolution one needs to analyze penetrating probes, such as direct photon or dilepton observables, as these particles are created throughout the evolution of the medium. In this paper we analyze an 1+3 dimensional analytic solution of relativistic hydrodynamics, and we calculate dilepton transverse momentum and invariant mass distributions. We investigate the dependence of dilepton production on time evolution parameters, such as emission duration and equation of state. Using parameters from earlier fits of this model to photon and hadron spectra, we compare our calculations to measurements as well. The most important feature of this work is that dilepton observables are calculated from an exact, analytic, 1+3D solution of relativistic hydrodynamics that is also compatible with hadronic and direct photon observables.Comment: 15 pages, 3 figure

    Initial temperature of the strongly interacting Quark Gluon Plasma created at RHIC

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    A 1+3 dimensional solution of relativistic hydrodynamics is analyzed in this paper. Momentum distribution and other observables are calculated from the solution and compared to hadronic measurements from the Relativistic Heavy Ion Collider (RHIC). The solution is compatible with the data, but only the freeze-out point of the evolution is determined. Many equation of states and initial states (initial temperatures) are valid with the same freeze-out distribution, thus the same hadronic observables. The observable that would distinguish between these initial temperatures is momentum distribution of photons, as photons are created throughout the evolution of the fireball created in RHIC collisions. The PHENIX experiment at RHIC measures such data via low invariant mass e+e- pairs. Average temperature from this data is T=221+-23+-18 MeV, while a model calculation with initial temperature 370 MeV agree with the data.Comment: Talk given at the Gribov-80 Memorial Workshop, May 26-28, 2010 ICTP Trieste, Italy. 12 pages, 5 figures. This work was supported by the OTKA grant NK73143 and M. Csanad's Bolyai scholarshi

    Interplay among the azimuthally dependent HBT radii and the elliptic flow

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    We present a calculation of the elliptic flow and azimuthal dependence of the correlation radii in the ellipsoidally symmetric generalization of the Buda-Lund model. The elliptic flow is shown to depend only on the flow anisotropy while in case of correlation radii both flow and space anisotropy play an important role in determining their azimuthal oscillation. We also outline a simple procedure for determining the parameters of the model from data.Comment: 7 pages, 4 figures, prepared with svjour.cls, accepted at Eur. Phys. J.
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