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)
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.
195334493
Quantum simulations of strongly coupled quark-gluon plasma
A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasi-particles is studied by a path-integral Monte-Carlo method. This approach is a quantum generalization of the classical molecular dynamics by Gelman, Shuryak, and Zahed. It is shown that this method is able to reproduce the QCD lattice equation of state. The results indicate that the QGP reveals liquid-like rather than gaslike properties. Quantum effects turned out to be of prime importance in these simulations.
118142337
Partial-transparency effects in high-energy collisions of heavy ions
A model is proposed for heavy-ion collisions at E/sub lab/approx.1 GeV/nucleon for the case of an incomplete statistical equilibrium in the highly excited nuclear matter. This approach can reproduce the characteristic double-humped structure of the experimental rapidity distributions of secondary particles.
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.
115321070
On the relationship between Boltzmann-Langevin and Boltzmann-Uehling-Uhlenbeck models
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.
117412426
Quark mass effects in QCD evolution equations and distribution functions of heavy quarks
We study the evolution equations of QCD taking the quark masses into account. The initial conditions of these equations, i.e., the quark and gluon distribution functions, are chosen at a sufficiently low Q/sup 2/ to allow one to use only the distribution functions of the light (valence) quarks and of the gluons. On the basis of a numerical solution of the evolution equations we have found the distribution functions of the heavy quarks, which display the correct threshold behavior: in the region Q/sup 2/<
6453654
Photoproduction of charmonia and total charmonium proton cross-sections
Elastic virtual photoproduction cross sections ${\ensuremath{\gamma}}^{*}\stackrel{\ensuremath{\rightarrow}}{p}J/\ensuremath{\psi}({\ensuremath{\psi}}^{\ensuremath{'}})p$ and total charmonium-nucleon cross sections for $J/\ensuremath{\psi}, {\ensuremath{\psi}}^{\ensuremath{'}},$ and $\ensuremath{\chi}$ states are calculated in a parameter-free way with the light-cone dipole formalism and the same input: factorization in impact parameters, light-cone wave functions for the ${\ensuremath{\gamma}}^{*}$ and the charmonia, and the universal phenomenological dipole cross section which is fitted to other data. The charmonium wave functions are calculated with four known realistic potentials, and two models for the dipole cross section are tested. Very good agreement with data for the cross section of charmonium photoproduction is found in a wide range of s and ${Q}^{2}.$ The inclusion of the Melosh spin rotation increases the ${\ensuremath{\psi}}^{\ensuremath{'}}$ photoproduction rate by a factor of 2\char21{}3 and removes previously observed discrepancies in the ${\ensuremath{\psi}}^{\ensuremath{'}}$ to $J/\ensuremath{\psi}$ ratio in photoproduction. We also calculate the charmonium-proton cross sections whose absolute values and energy dependences are found to correlate strongly with the sizes of the states.
119138207
Lepton flavor violating photoleptonic effect
We study lepton flavor violating analogs of the photoelectric effect, with a final μ or T instead of an electron: γe → μ and γe → T. On the basis of the general parametrization of the matrix element of the electromagnetic current we estimate the upper limits for the cross sections and event rates of these processes, imposed by the current experimental bounds on μ → ey and T → eγ decays.
126120440
Spectra Particles From $\Lambda_c^+$ and $\Sigma_c^{++}$ Charmed Baryon Decays Produced in Neutrino $N$ Interactions