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.
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.
119105321
New family of exact and rotating solutions of fireball hydrodynamics
A new class of analytic, exact, rotating, self-similar and surprisingly simple solutions of non-relativistic hydrodynamics are presented for a three-dimensionally expanding, spheroidally symmetric fireball. These results generalize earlier, non-rotating solutions for ellipsoidally symmetric fireballs with directional, three-dimensional Hubble flows. The solutions are presented for a general class of equations of state that includes the lattice QCD equations of state and may feature inhomogeneous temperature and corresponding density profiles.
118401873
New simple explicit solutions of perfect-fluid hydrodynamics and phase-space evolution
New exact solutions of relativistic perfect-fluid hydrodynamics are presented, including the first family of exact rotating solutions. The method used to search for them is a simultaneous investigation of the relativistic hydrodynamical equations and the collisionless Boltzmann equation. Possible connections to the evolution of hot and dense partonic matter in heavy-ion collisions is discussed.
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.
125371454
Decays A1 $\to \pi \rho$, A1 $\to \pi \gamma$ and $\pi^- \to e$ Anti-neutrino $\gamma$ in the Quark Model of the Superconductivity Type
7896037
Existence and Properties of the $f_0(665)$ State and Chiral Symmetry
On the basis of a simultaneous description of the isoscalar s-wave of $\pi\pi$ scattering (from the threshold up to 1.9 GeV) and of $\pi\pi\to K\bar{K}$ process (from the threshold to $\sim$ 1.4 GeV) in the model-independent approach, it is shown that there exists the $f_0(665)$ state with properies of the $\sigma$-meson, the glueball nature of $f_0(1500)$ is indicated, and the $f_0(1370)$ is assigned mainly to $s{\bar s}$ state. The coupling constants of the observed states with $\pi\pi$ and $K\bar{K}$ systems and scattering lengths $a_0^0(\pi\pi)$ and $a_0^0(K\bar{K})$ are calculated. The existence of the $f_0(665)$ state and the obtained $\pi\pi$-scattering length ($a_0^0\approx 0.27 m_{\pi^+}^{-1}$) seem to suggest the linear realization of chiral symmetry.
122638045
Low-energy hadronic interactions beyond the current algebra approach
Abstract Within chiral perturbation theory at the quark level (CHPT) q with linear realization of chiral U(3) × U(3) symmetry the new low-energy AP 3 -interaction, produced by convergent box-constituent-quark-loop diagrams, is obtained, and its contributions to processes of low-energy interactions of low-lying mesons are investigated. The new interaction goes beyond the framework of the low-energy current algebra approach and effective chiral Lagrangians with linear realization of chiral symmetry, constructed at the hadronic level.
122493642
On the problem of D-meson leptonic and semileptonic decays
Abstract The infinite mass effective theory, when a heavy quark mass goes to infinity, and chiral perturbation theory at the quark level, based on the extended Nambu-Jona-Lasinio model, are applied for the description of form factors of semileptonic decay D→ K e + ν e and leptonic constant FD of D-mesons. The relation is derived connecting the form factor f+(0) with the ratio F D F π , which gives the estimate F D F π =1.21±0.17 . The slope parameter of the f+ form factor is calculated in agreement with experimental data.
119339014
Nucleon structure from the quasithreshold inverse pion electroproduction
The process $\pi N\to e^+e^- N$ (IPE), being a natural and unique laboratory for studying the hadron electromagnetic structure in the sub-$N\bar{N}$-threshold time-like region of the virtual-photon ``mass'' $\lambda^2$, turns out to be also very useful for investigating the nucleon weak structure. A theoretical basis of the methods for extracting practically model-independent values of the electromagnetic hadron form factors in the time-like region and for determining the weak structure of the nucleon in the space-like region from experimental data on IPE at low energies is outlined. The results of extracting, by those methods, the electromagnetic $F_1^v(\lambda^2)$ and pseudoscalar $G_P(t)$ form-factors of a nucleon are presented, where an indication of the existence of the state $\pi^\p$ in the range 500-800 MeV (possibly the first radial excitation of pion) is obtained, and the coupling constant of this new state with the nucleon is estimated.