Transport Coefficients of Quark Gluon Plasma From Lattice Gauge Theory

Numerical results for the transport coefficients of quark gluon plasma are obtained by lattice simulations on on $16^3 \times 8$ lattice with the quench approximation where we apply the gauge action proposed by Iwasaki. The bulk viscosity is consistent with zero, and the shear viscosity is slightly smaller than the typical hadron masses. They are not far from the simple extrapolation on the figure of perturbative calculation in high temperature limit down to $T \sim T_{c}$. The gluon propagator in the confined and deconfined phases are also discussed.Comment: Quark Matter 97(talk at parallel session QCD) 4 pages in latex, 4 Postscript figure

Transport Coefficients of Quark Gluon Plasma for Pure Gauge Models

The transport coefficients of quark gluon plasma are calculated on a lattice 16**3X8, with the pure gauge models. Matsubara Green's functions of energy momentum tensors have very large fluctuations and about a few million MC sweeps are needed to reduce the errors reasonably small in the case of the standard action. They are much suppressed if Iwasaki's improved action is employed. Preliminary results show that the transport coefficients roughly depend on the coupling constant as a**(-3)(g) in the case of SU(2).Comment: Talk presented at LATTICE96(finite temperature), 3 pages in latex, 4 Postscript figure

Complementarity of Entanglement and Interference

A complementarity relation is shown between the visibility of interference and bipartite entanglement in a two qubit interferometric system when the parameters of the quantum operation change for a given input state. The entanglement measure is a decreasing function of the visibility of interference. The implications for quantum computation are briefly discussed.Comment: Final version, to appear on IJMPC; minor revision

Information Entropy in Cosmology

The effective evolution of an inhomogeneous cosmological model may be described in terms of spatially averaged variables. We point out that in this context, quite naturally, a measure arises which is identical to a fluid model of the `Kullback-Leibler Relative Information Entropy', expressing the distinguishability of the local inhomogeneous mass density field from its spatial average on arbitrary compact domains. We discuss the time-evolution of `effective information' and explore some implications. We conjecture that the information content of the Universe -- measured by Relative Information Entropy of a cosmological model containing dust matter -- is increasing.Comment: LateX, PRLstyle, 4 pages; to appear in PR

Compact Three Dimensional Black Hole: Topology Change and Closed Timelike Curve (minor changes)

We present a compactified version of the 3-dimensional black hole recently found by considering extra identifications and determine the analytical continuation of the solution beyond its coordinate singularity by extending the identifications to the extended region of the spacetime. In the extended region of the spacetime, we find a topology change and non-trivial closed timelike curves both in the ordinary 3-dimensional black hole and in the compactified one. Especially, in the case of the compactified 3-dimensional black hole, we show an example of topology change from one double torus to eight spheres with three punctures.Comment: 20 pages revtex.sty 8 figures contained, TIT/HEP-245/COSMO-4

Global constants in (2+1)--dimensional gravity

The extended conformal algebra (so)(2,3) of global, quantum, constants of motion in 2+1 dimensional gravity with topology R x T^2 and negative cosmological constant is reviewed. It is shown that the 10 global constants form a complete set by expressing them in terms of two commuting spinors and the Dirac gamma matrices. The spinor components are the globally constant holonomy parameters, and their respective spinor norms are their quantum commutators.Comment: 14 pages, to appear in Classical and Quantum Gravity, Spacetime Safari: Essays in Honor of Vincent Moncrief on the Classical Physics of Strong Gravitational Field

A Modular Invariant Quantum Theory From the Connection Formulation of (2+1)-Gravity on the Torus

By choosing an unconventional polarization of the connection phase space in (2+1)-gravity on the torus, a modular invariant quantum theory is constructed. Unitary equivalence to the ADM-quantization is shown.Comment: Latex, 4 page

Viscosities of Hot Gluon -- A Lattice QCD Study --

We present transport coefficients (shear viscosity, $\eta$, and bulk viscosity, $\zeta$) for the gluon system obtained by the lattice QCD. This is an indispensable calculation towards the understanding of ``New State of Matter'' observed in RHIC. We study the temperature regions of RHIC ($1.4 \leq T/T_c \leq 1.8$) and much higher ones up to $T/T_c \sim 20$. In RHIC regions, the ratio of shear viscosity to entropy density, $\eta/s$, is around $\sim 0.1-0.4$, and satisfies the KSS bound. At high temperature, $\eta$ becomes two or three oder of magnitude larger. Our calculation has two limitations: (i) the use of the quench approximation, i.e., without quark pair creation-annihilation effects on vacuum, and (ii) the use of an ansatz for the spectral function. The first point has been well studied in calculations of the spectroscopy and the phase-transition behavior. To investigate the second point, we compare our results with perturbative calculations in high $T$-regions, and also check the effects of the modification of the spectral function on the viscosity.Comment: 4 pages, 2 figures, contribution to Proceedings of Quark Matter 2005, Budapest, Aug 4-

The Black Hole in Three Dimensional Space Time

The standard Einstein-Maxwell equations in 2+1 spacetime dimensions, with a negative cosmological constant, admit a black hole solution. The 2+1 black hole -characterized by mass, angular momentum and charge, defined by flux integrals at infinity- is quite similar to its 3+1 counterpart. Anti-de Sitter space appears as a negative energy state separated by a mass gap from the continuous black hole spectrum. Evaluation of the partition function yields that the entropy is equal to twice the perimeter length of the horizon.Comment: This version is the one that appeared in PRL (1992), and has important improvements with respect to the one previously submitted to the archive. 13 pages, latex, no figure

Conductivity landscape of highly oriented pyrolytic graphite surface containing ribbons and edges

We present an extensive study on electrical spectroscopy of graphene ribbons and edges of highly oriented pyrolytic graphite (HOPG) using atomic force microscope (AFM). We have addressed in the present study two main issues, (1) How does the electrical property of the graphite (graphene) sheet change when the graphite layer is displaced by shear forces? and (2) How does the electrical property of the graphite sheet change across a step edge? While addressing these two issues we observed, (1) variation of conductance among the graphite ribbons on the surface of HOPG. The top layer always exhibits more conductance than the lower layers, (2) two different monolayer ribbons on the same sheet of graphite shows different conductance, (3) certain ribbon/sheet edges show sharp rise in current, (4) certain ribbons/sheets on the same edge shows both presence and absense of the sharp rise in the current, (5) some lower layers at the interface near a step edge shows a strange dip in the current/conductance (depletion of charge). We discuss possible reasons for such rich conducting landscape on the surface of graphite.Comment: 13 pages, 9 figures. For better quality figures please contact autho