5,097 research outputs found
SU(3) Gauge Theory with Adjoint Fermions
We analyze the finite temperature phase diagram of QCD with fermions in the
adjoint representation. The simulations performed with four dynamical Majorana
fermions, which is equivalent to two Dirac fermions, show that the
deconfinement and chiral phase transitions occur at two distinct temperatures,
. While the deconfinement transition
is first order we find evidence for a continuous chiral transition. We also
present potentials for and both for fundamental and adjoint fermion-antifermion pairs.Comment: LATTICE98(hightemp), 3 pages LaTeX2e, espcrc2 style, 6 eps figure
An analysis of new techniqes for radiometric correction of LANDSAT-4 Thematic Mapper images
The utility of methods for generating TM RLUTS which can improve the quality of the resultant images was investigated. The TM-CCT-ADDS tape was changed to account for a different collection window for the calibration data. Several scenes of Terrebonne Bay, Louisiana and the Grand Bahamas were analyzed to evaluate the radiometric corrections operationally applied to the image data and to investigate several techniques for reducing striping in the images. Printer plots for the TM shutter data were produced and detector statistics were compiled and plotted. These statistics included various combinations of the average shutter counts for each scan before and after DC restore for forward and reverse scans. Results show that striping is caused by the detectors becoming saturated when they view a bright cloud and depress the DC restore level
Results on Finite Density QCD
A brief summary of the formulation of QCD at finite chemical potental, ,
is presented. The failure of the quenched approximation to the problem is
reviewed.
Results are presented for dynamical simulations of the theory at strong and
intermediate couplings. We find that the problems associated with the quenched
theory persist: the onset of non-zero quark number does seem to occur at a
chemical potential . However analysis of the
Lee-Yang zeros of the grand canonical partition function in the complex
fugacity plane, (), does show signals of critical behaviour in the
expected region of chemical potential.
Results are presented for a simulation at finite density of the Gross-Neveu
model on a lattice near to the chiral limit. Contrary to our simulations
of QCD no pathologies were found when passed through the value
m_{\pi}/2}.Comment: 14 pages, Latex, 18 eps figures, Review for Tsukuba worksho
Flavor-Mixing Effects on the QCD Phase Diagram at non-vanishing Isospin Chemical Potential: One or Two Phase Transitions?
We investigate effects of a fixed nonzero isospin chemical potential on the
mu_B-T phase diagram of strongly interacting matter using a
Nambu--Jona-Lasinio-type four fermion interaction. We focus on the influence of
a flavor-mixing interaction induced by instantons. We find that already for
rather moderate values of the coupling strength in the flavor-mixing channel
the recent findings of two seperate phase transitions do not persist.Comment: 7 pages, 2 ps figure
The pseudo-Goldstone spectrum of 2-colour QCD at finite density
We examine the spectrum of 2-colour lattice QCD with 4 continuum flavours at
a finite chemical potential () for quark-number, on a
lattice. First we present evidence that the system undergoes a transition to a
state with a diquark condensate, which spontaneously breaks quark number at
, and that this transition is mean field in nature. We then
examine the 3 states that would be Goldstone bosons at for zero Dirac
and Majorana quark masses. The predictions of chiral effective Lagrangians give
a good description of the behaviour of these masses for . Except
for the heaviest of these states, these predictions diverge from our
measurements, once is significantly greater than . However, the
qualitative behaviour of these masses, indicates that the physics is very
similar to that predicted by these effective Lagrangians, and there is some
indication that at least part of these discrepancies is due to saturation, a
lattice artifact.Comment: 32 pages LaTeX/Revtex, 8 Postscript figure
Compact Lattice QED with Staggered Fermions and Chiral Symmetry Breaking
Different formulations of the compact lattice QED with staggered
fermions (standard Wilson and modified by suppression of lattice artifacts) are
investigated by Monte Carlo simulations within the quenched approximation. We
show that after suppressing lattice artifacts the system undergoes a phase
transition from the Coulomb phase into a presumably weakly chirally broken
phase only at (unphysical) negative --values.Comment: 7 pages, 5 figures attached in compressed postscript files, preprint
DESY-IfH and HU Berlin-IEP-94/11, submitted to Phys. Lett.
Non-Perturbative Renormalization Group Flows in Two-Dimensional Quantum Gravity
Recently a block spin renormalization group approach was proposed for the
dynamical triangulation formulation of two-dimensional quantum gravity. We use
this approach to examine non-perturbatively a particular class of higher
derivative actions for pure gravity.Comment: 17 page
3D two-color QCD at finite temperature and baryon density
We study the phase diagram for two-color QCD in three-dimensional spacetime,
as a function of temperature and baryon chemical potential, using the
low-energy effective Lagrangian approach. We show one-loop renormalizability at
zero temperature, and then use the one-loop effective Lagrangian at finite
temperature and chemical potential to show that at low temperature there is a
critical line separating the normal and diquark phase, with this critical line
ending at a tricritical point. This phase structure is qualitatively similar to
that found recently by Splittorff et al for two-color QCD in four-dimensional
spacetime, although the details are quite different, due to the different
symmetries and the different loop and infrared properties of three-dimensional
spacetime.Comment: 14 pp, 1 fi
Evidence for O(2) universality at the finite temperature transition for lattice QCD with 2 flavours of massless staggered quarks
We simulate lattice QCD with 2 flavours of massless quarks on lattices of
temporal extent N_t=8, to study the finite temperature transition from hadronic
matter to a quark-gluon plasma. A modified action which incorporates an
irrelevant chiral 4-fermion interaction is used, which allows simulations at
zero quark mass. We obtain excellent fits of the chiral condensates to the
magnetizations of a 3-dimensional O(2) spin model on lattices small enough to
model the finite size effects. This gives predictions for correlation lengths
and chiral susceptibilities from the corresponding spin-model quantities. These
are in good agreement with our measurements over the relevant range of
parameters. Binder cumulants are measured, but the errors are too large to draw
definite conclusions. From the properties of the O(2) spin model on the
relatively small lattices with which we fit our `data', we can see why earlier
attempts to fit staggered lattice data to leading-order infinite-volume scaling
functions, as well as finite size scaling studies, failed and led to erroneous
conclusions.Comment: 27 pages, Latex with 10 postscript figures. Some of the discussions
have been expanded to satisfy a referee. Typographical errors were correcte
Construction of nonlocal light-cone operators with definite twist
A systematic procedure is introduced to uniquely decompose nonlocal
LC-operators into harmonic operators of well defined geometric twist. The
method will be demonstrated for (pseudo)scalar, (axial) vector and skew tensor
bilocal quark light-ray operatorsComment: 4 pages, AMSTeX, Contribution to 7th Int. Workshop on Deep Inelastic
Scatterin and QCD, Zeuthen, April 1999 change of formulas 25 and 2
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