Thermodynamics of Quasi-Particles at Finite Chemical Potential

We present in this work a generalization of the solution of Gorenstein and Yang to the inconsistency problem of thermodynamics for systems of quasi-particles whose masses depend on both the temperature and the chemical potential. We work out several solutions for an interacting system of quarks and gluons and show that there is only one type of solution that reproduce both perturbative and lattice QCD.Comment: 33 pages, 1 figure. Accepted for publication in Nuclear Physics

Thermodynamics of Quasi-Particles

We present in this work a generalization of the solution of Gorenstein and Yang for a consistent thermodynamics for systems with a temperature dependent Hamiltonian. We show that there is a large class of solutions, work out three particular ones, and discuss their physical relevance. We apply the particular solutions for an ideal gas of quasi-gluons, and compare the calculation to lattice and perturbative QCD results.Comment: 26 pages, 1 figure. To appear in Nuclear Physics

Study on initial geometry fluctuations via participant plane correlations in heavy ion collisions: part II

Further investigation of the participant plane correlations within a Glauber model framework is presented, focusing on correlations between three or four participant planes of different order. A strong correlation is observed for $\cos(2\Phi_{2}^*+3\Phi_{3}^*-5\Phi_{5}^*)$ which is a reflection of the elliptic shape of the overlap region. The correlation between the corresponding experimental reaction plane angles can be easily measured. Strong correlations of similar geometric origin are also observed for $\cos(2\Phi_{2}^*+4\Phi_{4}^*-6\Phi_{6}^*)$, $\cos(2\Phi_2^*-3\Phi_3^*-4\Phi_4^*+5\Phi_5^*)$, $\cos(6\Phi_2^*+3\Phi_3^*-4\Phi_4^*-5\Phi_5^*)$, $\cos(\Phi_1^*-2\Phi_2^*-3\Phi_3^*+4\Phi_4^*)$, $\cos(\Phi_1^*+6\Phi_2^*-3\Phi_3^*-4\Phi_4^*)$, and $\cos(\Phi_1^*+2\Phi_2^*+3\Phi_3^*-6\Phi_6^*)$, which are also measurable. Experimental measurements of the corresponding reaction plane correlators in heavy ion collisions at RHIC and the LHC may improve our understanding of the physics underlying the measured higher order flow harmonics.Comment: 5 pages, 5 figure

A minimal quasiparticle approach for the QGP and its large-NcN_c limits

We propose a quasiparticle approach allowing to compute the equation of state of a generic gauge theory with gauge group SU($N_c$) and quarks in an arbitrary representation. Our formalism relies on the thermal quasiparticle masses (quarks and gluons) computed from Hard-Thermal-Loop techniques, in which the standard two-loop running coupling constant is used. Our model is minimal in the sense that we do not allow any extra ansatz concerning the temperature-dependence of the running coupling. We first show that it is able to reproduce the most recent equations of state computed on the lattice for temperatures higher than 2 $T_c$. In this range of temperatures, an ideal gas framework is indeed expected to be relevant. Then we study the accuracy of various inequivalent large-$N_c$ limits concerning the description of the QCD results, as well as the equivalence between the QCD$_{AS}$ limit and the ${\cal N}=1$ SUSY Yang-Mills theory. Finally, we estimate the dissociation temperature of the $\Upsilon$-meson and comment on the estimations' stability regarding the different considered large-$N_c$ limits.Comment: 19 pages, 6 figure

A method for studying initial geometry fluctuations via event plane correlations in heavy ion collisions

A method is proposed to measure the relative azimuthal angle distributions involving two or more event planes of different order in heavy ion collisions using a Fourier analysis technique. The analysis procedure is demonstrated for correlations involving two and three event planes (Phi_n, Phi_m and Phi_h). The Fourier coefficients of these distributions are found to coincide with previously proposed correlators, such as cos(6Phi_2-6Phi_3) and cos(Phi_1+2Phi_2-3Phi_3) etc, hence the method provides a natural framework for studying these correlators at the same time. Using a Monte Carlo Glauber model to simulate Au+Au collisions with fluctuating initial geometry, we are able to identify several new two- or three-plane correlators that have sizable magnitudes and should be measured experimentally.Comment: 10 pages, 14 figure