18872395
Quarkonium polarization in nonrelativistic QCD and the quark-gluon plasma
We examine angular distributions of leptons arising from the decay of $J/\ensuremath{\psi}$ in inclusive hadroproduction. Taking into account feed-down contributions from ${\ensuremath{\chi}}_{1,2},$ a flat distribution emerges without fine tuning parameters. Changes in the ratio of direct to total $J/\ensuremath{\psi}$ cross sections would change this distribution significantly. Such angular distributions are, therefore, confirmatory tests of the $J/\ensuremath{\psi}$ suppression signal for the production of a quark-gluon plasma. Related effects are predicted for the $\ensuremath{\Upsilon}.$
123580970
Implication of the EMC-effect on high transverse momentum jets
We show that the extension of nuclear structure functions to the regionx>1 can give rise to an enhancement of high-pT jet cross sections in hadron nucleus collisions. Such extensions are expected in a class of models proposed to explain the EMC-effect. Since these models are completely parametrized by the deep inelastic scattering data, the jet cross section emerge as parameter free predictions.
40481011
Quark number susceptibilities, strangeness, and dynamical confinement
We report the first results on the strange quark number susceptibility ${\ensuremath{\chi}}_{s}$ over a large range of temperatures, mainly in the plasma phase of QCD. ${\ensuremath{\chi}}_{s}$ jumps across the phase transition temperature ${T}_{c}$ and grows rapidly with temperature above but close to ${T}_{c}.$ For all quark masses and susceptibilities in the entire temperature range studied, we find a significant departure from ideal-gas values. We also observe a strong correlation between these quantities and the susceptibility in the pseudoscalar channel, supporting ideas of ``dynamical confinement'' in the high temperature phase of the QCD plasma.
14688147
Finding the critical end point of QCD: lattice and experiment
The current status of the search for the critical end point on the lattice and in experiments is discussed. A naive extrapolation is given of lattice results on the location of the critical end point to the continuum limit with the correct pion mass. An interpretation of current results on fluctuations is provided. A new method of analysis of experimental data is discussed, which provides a check on the removal of backgrounds, comparisons with QCD, and signals an approach to the critical end point.
119431013
A precise determination of T_c in QCD from scaling
Existing lattice data on the QCD phase transition are analyzed in renormalized perturbation theory. In quenched QCD it is found that T_c scales for lattices with only 3 time slices, and that T_c/Lambda_msbar=1.15 \pm 0.05. A preliminary estimate in QCD with two flavours of dynamical quarks shows that this ratio depends on the quark mass. For realistic quark masses we estimate T_c/Lambda_msbar=0.49 \pm 0.02. We also investigate the equation of state in quenched QCD at 1-loop order in renormalised perturbation theory.
119380357
A transport coefficient: the electrical conductivity
I describe the lattice determination of the electrical conductivity of the quark gluon plasma [6]. Since this is the first extraction of a transport coefficient with a degree of control over errors, I next use this to make estimates of other transport related quantities using simple kinetic theory formulae. The resulting estimates are applied to fluctuations, ultra-soft photon spectra and the viscosity. Dimming of ultra-soft photons is exponential in the mean free path, and hence is a very sensitive probe of transport.
117821951
Transverse Energy Distributions in Au + Au Collisions at 11.44 A GeV
121879312
Isobaric analog impurity from total and differential neutron scattering cross sections of silicon
Resonance parameters for sour resonances in Si have been obtained by analyzing measured differential neutron scattering cross sections combined with the total neutron cross section in the neutron energy range 1.05--1.40 MeV and applying R-matrix single channel multilevel theory. The resonance at 1254 krB has been identified as the s-wave analog resonance in /sup 29/Si. The identification also takes into account experimental radiative neutron capture data and shell model calculations for the radiative width. Estimates of the isospin mixing matrix elements are given.
18837917
Links Between Different Models for Multifragmentation
We establish links between three different models for multifragmentation: the percolation model, the lattice gas model and the statistical multifragmentation model. There are remarkable similarities between the lattice gas model and the statistical multifragmentation model. For completeness, we also compare with a model based upon classical molecular dynamics which gives rather different results.
118691839
Model for hypernucleus production in heavy ion collisions
We estimate the production cross sections of hypernuclei in projectile-like fragments (PLFs) in heavy ion collisions. The discussed scenario for the formation cross section of a LAMBDA hypernucleus is (a) LAMBDA particles are produced in the participant region but have a considerable rapidity spread and (b) LAMBDA with rapidity close to that of the PLF and total momentum (in the rest system of the PLF) up to Fermi motion can then be trapped and produce hypernuclei. Process (a) is considered here within the heavy ion jet interaction generator (HIJING/BB) model, and process (b) in the canonical thermodynamic model (CTM). We estimate the production cross sections for a hypernucleus {sub L}AMBDA{sup A}{sub F}Z where Z=1, 2, 3, and 4 for C + C at total nucleon-nucleon center of mass (c.m.) energy sq root(s{sub NN})=3.7 GeV, and for Ne + Ne and Ar + Ar collisions at sq root(s{sub NN})=5.0 GeV. By taking into account explicitly the impact parameter dependence of the colliding systems, it is found that the cross section is different from that predicted by the coalescence model, and large discrepancy is obtained for {sub L}AMBDA{sup 6}He and {sub L}AMBDA{sup 9}Be hypernuclei.
14798493
Effects of momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei
Abstract Using an isospin- and momentum-dependent transport model we study effects of the momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei. It is found that symmetry potentials with and without the momentum-dependence but corresponding to the same density-dependent symmetry energy E sym ( ρ ) lead to significantly different predictions on several E sym ( ρ )-sensitive experimental observables especially for energetic nucleons. The momentum- and density-dependence of the symmetry potential have to be determined simultaneously in order to extract the E sym ( ρ ) accurately. The isospin asymmetry of midrapidity nucleons at high transverse momenta is particularly sensitive to the momentum-dependence of the symmetry potential. It is thus very useful for investigating accurately the equation of state of dense neutron-rich matter.