288 research outputs found

    From kinetic theory to dissipative fluid dynamics

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    We present the results of deriving the Israel-Stewart equations of relativistic dissipative fluid dynamics from kinetic theory via Grad's 14-moment expansion. Working consistently to second order in the Knudsen number, these equations contain several new terms which are absent in previous treatments.Comment: 7 pages, proceedings of the Erice School on Nuclear Physics "Heavy Ion collisions from the Coulomb Barrier up to the Quark Gluon Plasma", Erice, Sicily, Sep. 16 - 24, 200

    Phase diagram of neutral quark matter at moderate densities

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    We discuss the phase diagram of moderately dense, locally neutral three-flavor quark matter using the framework of an effective model of quantum chromodynamics with a local interaction. The phase diagrams in the plane of temperature and quark chemical potential as well as in the plane of temperature and lepton-number chemical potential are discussed.Comment: 32 pages, 11 figures; contribution to the proceedings of the INT workshop "Pairing in fermionic systems", Seattle, September 19-23, 200

    The phase diagram of neutral quark matter: The effect of neutrino trapping

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    We study the effect of neutrino trapping on the phase diagram of dense, locally neutral three-flavor quark matter within the framework of a Nambu--Jona-Lasinio model. In the analysis, dynamically generated quark masses are taken into account self-consistently. The phase diagrams in the plane of temperature and quark chemical potential, as well as in the plane of temperature and lepton-number chemical potential are presented. We show that neutrino trapping favors two-flavor color superconductivity and disfavors the color-flavor-locked phase at intermediate densities of matter. At the same time, the location of the critical line separating the two-flavor color-superconducting phase and the normal phase of quark matter is little affected by the presence of neutrinos. The implications of these results for the evolution of protoneutron stars are briefly discussed.Comment: 10 pages, 9 figures, references added; version accepted for publication in Phys. Rev.

    The phase diagram of neutral quark matter: Self-consistent treatment of quark masses

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    We study the phase diagram of dense, locally neutral three-flavor quark matter within the framework of the Nambu--Jona-Lasinio model. In the analysis, dynamically generated quark masses are taken into account self-consistently. The phase diagram in the plane of temperature and quark chemical potential is presented. The results for two qualitatively different regimes, intermediate and strong diquark coupling strength, are presented. It is shown that the role of gapless phases diminishes with increasing diquark coupling strength.Comment: 10 pages, 7 figures. Two new figures added as in the published versio

    Results from RHIC with Implications for LHC

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    Results from the PHENIX experiment at RHIC in p-p and Au+Au collisions are reviewed from the perspective of measurements in p-p collisions at the CERN-ISR which serve as a basis for many of the techniques used. Issues such as J/Psi suppression and hydrodynamical flow in A+A collisions require data from LHC-Ions for an improved understanding. Suppression of high pT particles in Au+Au collisions, first observed at RHIC, also has unresolved mysteries such as the equality of the suppression of inclusive pi0 (from light quarks and gluons) and direct-single electrons (from the decay of heavy quarks) in the transverse momentum range 4< pT < 9 GeV/c. This disfavors a radiative explanation of suppression and leads to a fundamental question of whether the Higgs boson gives mass to fermions. Observation of an exponential distribution of direct photons in central Au+Au collisions for 1< pT <2 GeV/c where hard-processes are negligible and with no similar exponential distribution in p-p collisions indicates thermal photon emission from the medium at RHIC, making PHENIX at the moment ``the hottest experiment in Physics''.Comment: Invited lectures at the International School of Subnuclear Physics, 47th Course, "The most unexpected at LHC and the status of High Energy Frontier'', Erice, Sicily, Italy, August 29-September 7. 2009. 32 pages, 22 figure

    Vacuum phenomenology of the chiral partner of the nucleon in a linear sigma model with vector mesons

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    We investigate a linear sigma model with global chiral U(2)R×U(2)LU(2)_{R} \times U(2)_{L} symmetry. The mesonic degrees of freedom are the standard scalar and pseudoscalar mesons and the vector and axial-vector mesons. The baryonic degrees of freedom are the nucleon, NN, and its chiral partner, N∗N^{*}, which is usually identified with N(1535). The chiral partner is incorporated in the so-called mirror assignment, where the nucleon mass is not solely generated by the chiral condensate but also by a chirally invariant mass term, m0m_{0}. The presence of (axial-) vector fields modifies the expressions for the axial coupling constants of the nucleon, gANg_{A}^{N}, and its partner, gAN∗g_{A}^{N^{*}}. Using experimental data for the decays N∗→NπN^{*} \to N \pi and a1â†’Ï€Îła_{1} \to\pi\gamma, as well as lattice results for gAN∗g_{A}^{N^{*}} we infer m0∌500m_{0}\sim500 MeV, i.e., an appreciable amount of the nucleon mass originates from sources other than the chiral condensate. We test our model by evaluating the decay N∗→NηN^{*} \to N \eta and the s-wave nucleon-pion scattering lengths a0(±)a_{0}^{(\pm)}.Comment: 16 pages, 2 figures. To appear in Phys. Rev.

    Simple solutions of fireball hydrodynamics for self-similar elliptic flows

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    Simple, self-similar, elliptic solutions of non-relativistic fireball hydrodynamics are presented, generalizing earlier results for spherically symmetric fireballs with Hubble flows and homogeneous temperature profiles. The transition from one dimensional to three dimensional expansions is investigated in an efficient manner.Comment: 12 pages, 4 figures in 8 .eps files, references to recent data added, accepted in Physics Letters

    Effective Gap Equation for the Inhomogeneous LOFF Superconductive Phase

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    We present an approximate gap equation for different crystalline structures of the LOFF phase of high density QCD at T=0. This equation is derived by using an effective condensate term obtained by averaging the inhomogeneous condensate over distances of the order of the crystal lattice size. The approximation is expected to work better far off any second order phase transition. As a function of the difference of the chemical potentials of the up and down quarks, ÎŽÎŒ\delta\mu, we get that the octahedron is energetically favored from ÎŽÎŒ=Δ0/2\delta\mu=\Delta_0/\sqrt 2 to 0.95Δ00.95\Delta_0, where Δ0\Delta_0 is the gap for the homogeneous phase, while in the range 0.95Δ0−1.32Δ00.95\Delta_0-1.32\Delta_0 the face centered cube prevails. At ÎŽÎŒ=1.32Δ0\delta\mu=1.32\Delta_0 a first order phase transition to the normal phase occurs.Comment: 11 pages, 5 figure
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