1,902 research outputs found
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 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 . 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
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
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
Viscosities of Hot Gluon -- A Lattice QCD Study --
We present transport coefficients (shear viscosity, , and bulk
viscosity, ) 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 () and much higher ones up to . In RHIC regions,
the ratio of shear viscosity to entropy density, , is around , and satisfies the KSS bound. At high temperature, 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 -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
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