116272686
Dynamical Instabilities in Relativistic Heavy-Ion Collisions and Associated Phenomena
119351822
Equation of state of deconfined matter within a dynamical quasiparticle description
A simple quasiparticle model, motivated by lowest-order perturbative QCD, is proposed. It is applied to interpret the lattice QCD equation of state. A reasonable reproduction of the lattice data is obtained. In contrast to existing quasiparticle models, the present model is formulated in dynamical rather than thermodynamical terms, and is easily applicable to a system with finite baryon density. In particular, the model simulates the confinement property.
122934808
Relativistic mean field kinetic approach to hadron plasma and three-fluid dynamics
Abstract Proceeding from the Walecka mean field theory, a system of relativistic kinetic equations has been derived for the description of hadron plasma formation and evolution in nucleus-nucleus collisions at high energies. These equations comprise the dynamics of relativistic self-consistent σ and ω fields and, in particular, satisfactorily described ground states of nuclei. The constructed collision integrals are expressed via inclusive hadron-hadron cross sections and allow one to describe inelastic production of new particles in the process of the nucleus-nucleus collision. A method of solving these kinetic equations, based on a model representation of distribution functions, is proposed. An ansatz for the distribution functions is constructed proceeding from the assumption of incomplete stopping of nuclei in the collision process. This ansatz make it possible to reduce the set of kinetic equations to a set of equations of the three-fluid dynamics type for the parameters of the distribution functions.
14791019
Lattice QCD constraints on hybrid and quark stars
A QCD-motivated dynamical-quasiparticle model with parameters adjusted to reproduce the lattice-QCD equation of state is extrapolated from the region of high temperatures and moderate baryonic densities to the domain of high baryonic densities and zero temperature. The resulting equation of state matched with realistic hadronic equations of state predicts a phase transition into the quark phase at higher densities than those reachable in neutron star interiors. This excludes the possibility of the existence of hybrid (hadron-quark) stars. Pure quark stars are possible and have low masses, small radii, and very high central densities. Similar results are obtained for a simple bag model with massive quarks, fitted to reproduce the same lattice results. Self-bound quark matter is also excluded within these models. Uncertainties in the present extrapolation are discussed. Comparison with standard bag models is made.
18368050
Equation of State of Strongly Coupled Quark–Gluon Plasma – Path Integral Monte Carlo Results
A strongly coupled plasma of quark and gluon quasiparticles at temperatures from 1.1Tc to 3Tc is studied by path integral Monte Carlo simulations. This method extends previous classical nonrelativistic simulations based on a color Coulomb interaction to the quantum regime. We present the equation of state and find good agreement with lattice results. Further, pair distribution functions and color correlation functions are computed indicating strong correlations and liquid-like behavior (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
16049954
Soft modes, resonances, and quantum transport
Effects of the propagation of particles that have a finite lifetime and an according width in their mass spectrum are discussed in the context of transport description. First, the importance of coherence effects (Landau-Pomeranchuk-Migdal effect) on the production and absorption of field quanta in nonequilibrium dense matter is considered. It is shown that classical diffusion and Langevin results correspond to a resummation of certain field-theory diagrams formulated in terms of full nonequilibrium Green's functions. General properties of broad resonances in dense and hot systems are discussed in the framework of a self-consistent and conserving Φ-derivable method of Baym by considering the examples of the ρ meson in hadronic matter and the pion in dilute nuclear matter. Further, we address the problem of a transport description that properly takes into account the damping width of the particles. The Φ-derivable method generalized to the real-time contour provides a selfconsistent and conserving kinetic scheme. We derive a generalized expression for the nonequilibrium kinetic entropy flow, which includes corrections from fluctuations and mass-width effects. In special cases, an H theorem is proven. Memory effects in collision terms contribute to the kinetic entropy flow that, in the Fermi liquid case, reproduces the famous bosonic-type T3lnT correction to the specific heat of liquid 3He. For the example of the pion-condensate phase transition in dense nuclear matter, we demonstrate the important role of the width effects within the quantum transport.
124707884
The Decay $\tau \to 3 \pi \nu_\tau$ and Characteristics of $A1$ Meson
The phenomenological meson Lagrangian based on the four-quark interactions of the scalar, pseudoscalar, vector and axial-vector types is used for description of the decay τ−→π+π−π−vτ. The structure of the main hadronic vertexa 1 − ρπ is discussed. The expression for the axial hadronic currentJμ(a1→3π) is obtained. The low-energy limit of this current is analysed. Spectral functions for the main channel of the given process are calculated. The fitting of the experimental data leads to the following values of thea1 parameters: 
 
$$\begin{gathered} m_{a_1 } = 1242 \pm 37MeV,\Gamma _{a_1 } = 465_{ - 143}^{ + 228} MeV\left( {DELCO} \right); \hfill \\ \hfill \\ m_{a_1 } = 1260 \pm 14MeV,\Gamma _{a_1 } = 298_{ - 34}^{ + 40} MeV\left( {MARK II} \right); \hfill \\ \hfill \\ m_{a_1 } = 1250 \pm 9MeV,\Gamma _{a_1 } = 488 \pm 32MeV\left( {ARGUS} \right). \hfill \\ \end{gathered} $$
126372642
Logarithmic and Power Scaling Violation in Lepton Deep Inelastic Scattering. Data {QCD} Analysis
117569877
Lepton-nucleon scattering in the relativistic oscillator model
The scattering of charged leptons by a system of three quarks locked in by a relativistic oscillator potential is considered. The calculations are performed in the rest frame of the target, which allows the derivation of the explicit x and Q/sup 2/ dependences of the nucleon structure functions F/sub 1/(x,Q/sup 2/) and F/sub 2/(x,Q/sup 2/) and the quantity R = sigma/sub L//sigma/sub T/ in the region of moderate Q/sup 2/ values.
120657056
Radiative tau decay into pion
The possibility of the experimental investigation of the radiative tau decay into pion is discussed including background conditions. The decay width is estimated to be Br(τ→vτπγ)=0.15% (at the minimal registered photon energy 50 MeV). The contribution of the structural component is 10% of the total radiation. The main background is produced by photons from the τ→vτπ−π0 decay. We investigate the angular and energy spectra of the decay products and analyse the background conditions. The kinematic region was found where the structural radiation dominates over background.
896237
Electroproduction of charmonia off nuclei
In a recent publication we have calculated elastic charmonium production in ep collisions employing realistic charmonia wave functions and dipole cross sections and have found good agreement with the data in a wide range of s and Q^2. Using the ingredients from those calculations we calculate exclusive electroproduction of charmonia off nuclei. Here new effects become important, (i) color filtering of the c-cbar pair on its trajectory through nuclear matter, (ii) dependence on the finite lifetime of the c-cbar fluctuation (coherence length) and (iii) gluon shadowing in a nucleus compared to the one in a nucleon. Total coherent and incoherent cross sections for C, Cu and Pb as functions of s and Q^2 are presented together with some differential cross sections. The results can be tested with future electron-nucleus colliders or in peripheral collisions of ultrarelativistic heavy ions.