118504696
Exact solutions of relativistic perfect fluid hydrodynamics for a QCD Equation of State
We generalize a previously known class of exact analytic solutions of relativistic perfect fluid hydrodynamics for the first time to arbitrary temperature-dependent Equation of State. We investigate special cases of this class of solutions, in particular, we present hydrodynamical solutions with an Equation of State determined from lattice QCD calculations. We discuss the phenomenological relevance of these solutions as well.
119143405
Detailed description of accelerating, simple solutions of relativistic perfect fluid hydrodynamics
In this paper we describe in full details a new family of recently found exact solutions of relativistic, perfect fluid dynamics. With an ansatz that generalizes the well-known Hwa-Bjorken solution we obtain a wide class of new exact, explicit, and simple solutions, which have a remarkable advantage as compared to presently known exact and explicit solutions: they do not lack acceleration. They can be utilized for the description of the evolution of the matter created in high energy heavy ion collisions. Because these solutions are accelerating, they provide a more realistic picture than the well-known Hwa-Bjorken solution, and give more insight into the dynamics of the matter. We exploit this by giving an advanced simple estimation of the initial energy density of the produced matter in high energy collisions, which takes acceleration effects, i.e., the work done by the pressure, and the modified change of the volume elements, into account. We also give an advanced estimation of the life-time of the reaction. Our new solutions can also be used to test numerical hydrodynamical codes reliably. In the end, we also give an exact, 1+1 dimensional, relativistic hydrodynamical solution, where the initial pressure and velocity profile is arbitrary, and we showmore » that this general solution is stable for perturbations.« less
16863322
Multi-boson correlations using wave-packets II
Abstract.
We investigate the analytically solvable pion-laser model, and generalize it to arbitrary multiplicity distributions.
We show that this kind of extension of the model is possible, but less interesting, than the already known one.
15716297
New exact solutions of relativistic hydrodynamics
A new class of simple and exact solutions of relativistic hydrodynamics is presented, and the consequences are explored in data analysis. The effects of longitudinal work and acceleration are taken into account in an advanced estimate of the initial energy density and the life-time of the reaction.
125071872
Exact solutions of perfect fluid hydrodynamics: Theory and applications in high-energy experiments
Some exact and explicit solutions of the relativistic hydrodynamical equations are reviewed in context of high-energy heavy ion physics. Hydrodynamics is a powerful tool to describe the experimentally observed features (e.g. scaling laws) in the final state of high-energy collisions. Hydrodynamical solutions (both exact, analytic and numerical) can then be used to draw consequences on the initial state or the equation of state of the created matter. These findings can help to reach the ultimate goal of heavy-ion physics, the mapping of the phase structure of the strong interaction. In this paper we discuss exact and phenomenologically relevant solutions of hydrodynamics, and hint at some applications of them. We detail one important application: the estimation of the initial energy density from the observed final state.
30878089
Accelerating solutions of perfect fluid hydrodynamics for initial energy density and life-time measurements in heavy ion collisions
A new class of accelerating, exact, explicit and simple solutions of relativistic hydrodynamics is presented. Since these new solutions yield a finite rapidity distribution, they lead to an advanced estimate of the initial energy density and life-time of high energy heavy ion collisions. Accelerating solutions are also given for spherical expansions in arbitrary number of spatial dimensions.
118774621
Pion nucleon coupling constant, Goldberger-Treiman discrepancy and $\pi N$ $\sigma$ term
We start by studying the Goldberger-Treiman discrepancy (GTd) $\Delta = (2.259\pm 0.591)%$. Then we look at the $\pi N$ $\sigma$ term, with the dimensionless ratio $\sigma_N/2m_N=3.35%$. Finally we return to predicting (via the quark model) the $\pi N$ coupling constant, with GTd $\Delta\to 0$ as $m_q\to m_N/3$.
15150236
Effective quark model with chiral U(3) x U(3) symmetry for baryon octet and decuplet
We suggest an effective quark model for low-lying baryon octet and decuplet motivated by QCD with a linearly rising confinement potential incorporating the extended Nambu--Jona-Lasinio (ENJL) model with linear realization of chiral $U(3)\ifmmode\times\else\texttimes\fi{}U(3)$ symmetry. Baryons are considered as external heavy states coupled to local three-quark currents with fixed spinorial structure and to low-lying mesons through quark-meson interactions defined in the ENJL model. In the constituent quark loop representation we have calculated the coupling constants of the $\ensuremath{\pi}NN, \ensuremath{\pi}N\ensuremath{\Delta},$ and $\ensuremath{\gamma}N\ensuremath{\Delta}$ interactions and the ${\ensuremath{\sigma}}_{\ensuremath{\pi}N}$ term. The obtained results are in reasonable agreement with experimental data and other effective field theory approaches.