Leptonic Observables in Ultra-Relativistic Heavy Ion Collisions

We report on leptonic observables by the PHENIX experiment from data taken during Run II at the Relativistic Heavy Ion Collider (RHIC). We show first results on phi -> K+K-, e+e-, low and intermediate mass dielectron continuum, single electrons from charm, and J/psi yields in proton-proton and Au-Au collisions at sqrt{s_{NN}}=200 GeV.Comment: 10 pages, 11 figures, Talk presented at Quark Matter 2002, Nantes, France, July 18-24, 2002. To appear in the proceedings (Nucl. Phys. A

E864: Experimental Results on Exotic Nuclei and Rare Probes

Experiment 864 at the BNL-AGS was designed to search for exotic states of strange quark matter and other rare composite particles. The experiment was commissioned in 1994 and completed its final run in 1998. Here, we present an overview of the experimental results for the production of light nuclei up to A=7, antiprotons and antideuterons, hypernuclei and production limits on new states of quark matter.Comment: 6 pages, 6 figures, quark matter 1999 conference proceeding

New Scaling Law for Deuteron Production in Ultra-Relativistic Nucleus Nucleus Collisions

Deuteron production in S and Pb induced collisions at beam energies of 200 and 160 AGeV is studied in the framework of the transport theoretical approach RQMD. Strong transverse flow invalidates the differential coalescence formula in momentum space. The transverse momentum integrated $d$ yields scale in a broad rapidity interval with the squared proton densities and inversely with the produced particle rapidity densities. This kind of scaling can be linked to constant relative sizes of nucleon and pion sources at freeze-out. With increasing projectile mass the nucleon source blows up stronger than the pion source. As a result, the scaled deuteron densities drop in central Pb+Pb collisions by 15 percent as compared to S induced reactions.Comment: 12 pages + 4 postscript figures (uuencoded and included

Parity-Violating Interaction Effects I: the Longitudinal Asymmetry in pp Elastic Scattering

The proton-proton parity-violating longitudinal asymmetry is calculated in the lab-energy range 0--350 MeV, using a number of different, latest-generation strong-interaction potentials--Argonne V18, Bonn-2000, and Nijmegen-I--in combination with a weak-interaction potential consisting of rho- and omega-meson exchanges--the model known as DDH. The complete scattering problem in the presence of parity-conserving, including Coulomb, and parity-violating potentials is solved in both configuration- and momentum-space. The predicted parity-violating asymmetries are found to be only weakly dependent upon the input strong-interaction potential adopted in the calculation. Values for the rho- and omega-meson weak coupling constants $h^{pp}_\rho$ and $h^{pp}_\omega$ are determined by reproducing the measured asymmetries at 13.6 MeV, 45 MeV, and 221 MeV.Comment: 24 pages, 8 figures, submitted to Physical Review

Energy Loss of a Heavy Fermion in an Anisotropic QED Plasma

We compute the leading-order collisional energy loss of a heavy fermion propagating in a QED plasma with an electron distribution function which is anisotropic in momentum space. We show that in the presence of such anisotropies there can be a significant directional dependence of the heavy fermion energy loss with the effect being quite large for highly-relativistic velocities. We also repeat the analysis of the isotropic case more carefully and show that the final result depends on the intermediate scale used to separate hard and soft contributions to the energy loss. We then show that the canonical isotropic result is obtained in the weak-coupling limit. For intermediate-coupling we use the residual scale dependence as a measure of our theoretical uncertainty. We also discuss complications which could arise due to the presence of unstable soft photonic modes and demonstrate that the calculation of the energy loss is safe.Comment: 19 pages, 18 figures. v2 - Correction to normalization of numerical results; some figures modified as a result; discussion of role of unstable modes added along with two new figure

Does the Charm Flow at RHIC?

Recent PHENIX Au+Au -> e- + X data from open charm decay are shown to be consistent with two extreme opposite dynamical scenarios of ultra-relativistic nuclear reactions. Perturbative QCD without final state interactions was previously shown to be consistent with the data. However, we show that the data are also consistent with zero mean free path hydrodynamics characterized by a common transverse flow velocity field. The surprising coincidence of both D and B hydrodynamic flow spectra with pQCD up to p_T ~ 3 and 5 GeV, respectively, suggests that heavy quarks may be produced essentially at rest in the rapidly expanding gluon plasma. Possible implications and further tests of collective heavy quark dynamics are discussed.Comment: 10 pages, 3 figures, submitted to Phys. Lett.

Baryon phase-space density in heavy-ion collisions

The baryon phase-space density at mid-rapidity from central heavy-ion collisions is estimated from proton spectra with interferometry and deuteron coalescence measurements. It is found that the mid-rapidity phase-space density of baryons is significantly lower at the SPS than the AGS, while those of total particles (pion + baryon) are comparable. Thermal and chemical equilibrium model calculations tend to over-estimate the phase-space densities at both energies.Comment: 5 pages, 2 tables, no figure. RevTeX style. Accepted for publication in Phys. Rev. C Rapid Communicatio

Discrete kink dynamics in hydrogen-bonded chains I: The one-component model

We study topological solitary waves (kinks and antikinks) in a nonlinear one-dimensional Klein-Gordon chain with the on-site potential of a double-Morse type. This chain is used to describe the collective proton dynamics in quasi-one-dimensional networks of hydrogen bonds, where the on-site potential plays role of the proton potential in the hydrogen bond. The system supports a rich variety of stationary kink solutions with different symmetry properties. We study the stability and bifurcation structure of all these stationary kink states. An exactly solvable model with a piecewise ``parabola-constant'' approximation of the double-Morse potential is suggested and studied analytically. The dependence of the Peierls-Nabarro potential on the system parameters is studied. Discrete travelling-wave solutions of a narrow permanent profile are shown to exist, depending on the anharmonicity of the Morse potential and the cooperativity of the hydrogen bond (the coupling constant of the interaction between nearest-neighbor protons).Comment: 12 pages, 20 figure

Evolution of the differential transverse momentum correlation function with centrality in Au+Au collisions at sNN=200\sqrt{s_{NN}} = 200 GeV

We present first measurements of the evolution of the differential transverse momentum correlation function, {\it C}, with collision centrality in Au+Au interactions at $\sqrt{s_{NN}} = 200$ GeV. {\it C} exhibits a strong dependence on collision centrality that is qualitatively similar to that of number correlations previously reported. We use the observed longitudinal broadening of the near-side peak of {\it C} with increasing centrality to estimate the ratio of the shear viscosity to entropy density, $\eta/s$, of the matter formed in central Au+Au interactions. We obtain an upper limit estimate of $\eta/s$ that suggests that the produced medium has a small viscosity per unit entropy.Comment: 7 pages, 4 figures, STAR paper published in Phys. Lett.

System Size and Energy Dependence of Jet-Induced Hadron Pair Correlation Shapes in Cu+Cu and Au+Au Collisions at sqrt(s_NN) = 200 and 62.4 GeV

We present azimuthal angle correlations of intermediate transverse momentum (1-4 GeV/c) hadrons from {dijets} in Cu+Cu and Au+Au collisions at sqrt(s_NN) = 62.4 and 200 GeV. The away-side dijet induced azimuthal correlation is broadened, non-Gaussian, and peaked away from \Delta\phi=\pi in central and semi-central collisions in all the systems. The broadening and peak location are found to depend upon the number of participants in the collision, but not on the collision energy or beam nuclei. These results are consistent with sound or shock wave models, but pose challenges to Cherenkov gluon radiation models.Comment: 464 authors from 60 institutions, 6 pages, 3 figures, 2 tables. Submitted to Physical Review Letters. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm