Transport theory with self-consistent confinement related to the lattice data

The space-time development of a quark-gluon plasma is calculated from a Vlasov equation for the distribution function of quasiparticles with medium dependent masses. At each space-time point the masses are calculated selfconsistently from a gap equation, whose form is determined by the requirement that in thermal equilibrium and for a range of temperatures the energy density of the quasi-particle system is identical to the one from lattice calculations . The numerical solutions of the Vlasov equation display confinement. Relations to effective theories like that by Friedberg Lee and Nambu Jona-Lasinio are established.Comment: 9 pages, 12 figure

Transverse energy dependence of J/Psi suppression in Au+Au collisions at RHIC energy

Prediction for transverse energy dependence of $J/\psi$ to Drell-Yan ratio in Au+Au collisions at RHIC energy was obtained in a model which assume 100% absorption of $J/\psi$ above a threshold density. The threshold density was obtained by fitting the NA50 data on $J/\psi$ suppression in Pb+Pb collisions at SPS energy. At RHIC energy, hard processes may be important. Prediction of $J/\psi$ suppression with and without hard processes were obtained. With hard processes included, $J/\psi$'s are strongly suppressed.Comment: 4 pages, 2 figures (revised version

Nonlocal field correlators on the lattice in HP^1 sigma-model

Connected two-point field strength correlators have been measured on the lattice in quaternionic projective sigma-model of pure SU(2) Yang-Mills theory. The correlation lengths, extracted from the exponential fit for these correlators, are found to be lambda_1^{-1} = 1.40(3) GeV and lambda^{-1} = 1.51(3) GeV in good agreement with other existing calculations. The dependence of bilocal functions on the connector shape was studied.Comment: 11 pages, 9 figures, to be published in JETP Letter

A Bound on the Energy Loss of Partons in Nuclei

We derive a quantum mechanical upper bound on the amount of radiative energy loss suffered by high energy quarks and gluons in nuclear matter. The bound shows that the nuclear suppression observed in quarkonium production at high $x_F$ cannot be explained in terms of energy loss of the initial or final parton states. We also argue that no nuclear suppression is expected in the photoproduction of light hadrons at large $x_F$.Comment: 15 pages, 1 figure included as a Postscript file, phyzzx.te

Momentum dependence of the energy gap in the superconducting state of optimally doped Bi2(Sr,R)2CuOy (R=La and Eu)

The energy gap of optimally doped Bi2(Sr,R)2CuOy (R=La and Eu) was probed by angle resolved photoemission spectroscopy (ARPES) using a vacuum ultraviolet laser (photon energy 6.994 eV) or He I resonance line (21.218 eV) as photon source. The results show that the gap around the node at sufficiently low temperatures can be well described by a monotonic d-wave gap function for both samples and the gap of the R=La sample is larger reflecting the higher Tc. However, an abrupt deviation from the d-wave gap function and an opposite R dependence for the gap size were observed around the antinode, which represent a clear disentanglement between the antinodal pseudogap and the nodal superconducting gap.Comment: Submitted as the proceedings of LT2

Nuclear Coherent versus Incoherent Effects in Peripheral RHI Collisions

We derive simple and physically transparent expressions for the contribution of the strong interaction to one nucleon removal processes in peripheral relativistic heavy ion collisions. The coherent contribution,i.e, the excitation of a giant dipole resonance via meson exchange is shown to be negligible as well as interference between coulomb and nuclear excitation. Incoherent nucleon knock out contribution is also derived suggesting the nature of the nuclear interaction in this class of processes. We also justify the simple formulae used to fit the data of the E814 Collaboration.Comment: LATEX, 20 pags, Submited to Nucl. Phys. C, NUCPHA 176

Photoelectron Escape Depth and Inelastic Secondaries in High Temperature Superconductors

We calculate the photoelectron escape depth in the high temperature superconductor Bi2212 by use of electron energy-loss spectroscopy data. We find that the escape depth is only 3 Ang. for photon energies typically used in angle resolved photoemission measurements. We then use this to estimate the number of inelastic secondaries, and find this to be quite small near the Fermi energy. This implies that the large background seen near the Fermi energy in photoemission measurements is of some other origin.Comment: 2 pages, revtex, 3 encapsulated postscript figure

ARPES on HTSC: simplicity vs. complexity

A notable role in understanding of microscopic electronic properties of high temperature superconductors (HTSC) belongs to angle resolved photoemission spectroscopy (ARPES). This technique supplies a direct window into reciprocal space of solids: the momentum-energy space where quasiparticles (the electrons dressed in clouds of interactions) dwell. Any interaction in the electronic system, e.g. superconducting pairing, leads to modification of the quasi-particle spectrum--to redistribution of the spectral weight over the momentum-energy space probed by ARPES. A continued development of the technique had an effect that the picture seen through the ARPES window became clearer and sharper until the complexity of the electronic band structure of the cuprates had been resolved. Now, in an optimal for superconductivity doping range, the cuprates much resemble a normal metal with well predicted electronic structure, though with rather strong electron-electron interaction. This principal disentanglement of the complex physics from complex structure reduced the mystery of HTSC to a tangible problem of interaction responsible for quasi-particle formation. Here we present a short overview of resent ARPES results, which, we believe, denote a way to resolve the HTSC puzzle.Comment: A review written for a special issue of FN

Azimuthal asymmetry of J/Psi suppression in non-central heavy-ion collisions

The azimuthal asymmetry of $J/\psi$ suppression in non-central heavy-ion collisions is studied within a dynamic model of $J/\psi$ suppression in a deconfined partonic medium. Within this model, $J/\psi$ suppression in heavy-ion collisions is caused mainly by the initial state nuclear absorption and dissociation via gluon-$J/\psi$ scattering in deconfined partonic medium. Only the second mechanism gives arise to azimuthal asymmetry of the final $J/\psi$ production. We demonstrate that if there is an onset of suppression by quark-gluon plasma (QGP) in the NA50 data, it must be accompanied by the non-vanishing azimuthal asymmetry. Using the same critical density above which the QGP effect enters, we predict the azimuthal asymmetric coefficient $v_2$ as well as the survival probability for $J/\psi$ at the RHIC energy.Comment: 10 pages, 2 EPS figures, final version in Phys. Lett.

Phase Structure of Nambu-Jona-Lasinio Model at Finite Isospin Density

In the frame of flavor SU(2) Nambu--Jona-Lasinio model with $U_A(1)$ breaking term we found that, the structure of two chiral phase transition lines does not exist at low isospin density in real world, and the critical isospin chemical potential for pion superfluidity is exactly the pion mass in the vacuum.Comment: 8 pages, submitted to Phys.Lett.