1,115 research outputs found
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We explain why compact U(1) confines and how to fix it. We show that
plaquettes of negative trace carry most of the confinement signal in compact
SU(2). We show how to perform noncompact gauge-invariant simulations without
auxiliary fields. We suggest a way to simulate fermions without doublers.Comment: Talk presented at LATTICE96(algorithms), 4 pages, Latex, espcrc2,
picte
Noncompact Gauge-Invariant Simulations of U(1), SU(2), and SU(3)
We have applied a new gauge-invariant, noncompact, Monte Carlo method to
simulate the , , and gauge theories on and
lattices. The Creutz ratios of the Wilson loops agree with the exact results
for for apart from a renormalization of the charge. The
and Creutz ratios robustly display quark confinement at and , respectively. At much weaker coupling, the and
Creutz ratios agree with perturbation theory after a renormalization of
the coupling constant. For the scaling window is near ,
and the relation between the string tension and our lattice QCD
parameter is .Comment: For U(1), we switched from beta = 2 / g^2 to beta = 1 / g^2; 3 pages;
latex and espcrc2.sty; one figure generated by PiCTeX; our contribution to
Lattice '9
Low temperature expansion for the 3-d Ising Model
We compute the weak coupling expansion for the energy of the three
dimensional Ising model through 48 excited bonds. We also compute the
magnetization through 40 excited bonds. This was achieved via a recursive
enumeration of states of fixed energy on a set of finite lattices. We use a
linear combination of lattices with a generalization of helical boundary
conditions to eliminate finite volume effects.Comment: 10 pages, IASSNS-HEP-92/42, BNL-4767
Properties of the vector meson nonet at large N_c beyond the chiral limit
Masses and especially coupling constants of the vector meson nonet are
determined in the large-N_c limit, but beyond the chiral limit taking into
account terms up to quadratic order in the Goldstone boson masses. With two
input parameters five coupling constants for hadronic and dilepton decays are
determined which agree very well with the experimental results. The obtained
parameters are also used to calculate the pion and kaon decay constant in the
large-N_c limit. A consistent picture is only obtained, if the correct
assignment of the N_c-dependence of the electromagnetic charges of the quarks
is taken into account.Comment: 12 pages, strongly rewritten, more focussed on the central issu
End states, ladder compounds, and domain wall fermions
A magnetic field applied to a cross linked ladder compound can generate
isolated electronic states bound to the ends of the chain. After exploring the
interference phenomena responsible, I discuss a connection to the domain wall
approach to chiral fermions in lattice gauge theory. The robust nature of the
states under small variations of the bond strengths is tied to chiral symmetry
and the multiplicative renormalization of fermion masses.Comment: 10 pages, 4 figures; final version for Phys. Rev. Let
Series expansions without diagrams
We discuss the use of recursive enumeration schemes to obtain low and high
temperature series expansions for discrete statistical systems. Using linear
combinations of generalized helical lattices, the method is competitive with
diagramatic approaches and is easily generalizable. We illustrate the approach
using the Ising model and generate low temperature series in up to five
dimensions and high temperature series in three dimensions. The method is
general and can be applied to any discrete model. We describe how it would work
for Potts models.Comment: 24 pages, IASSNS-HEP-93/1
Chiral Symmetry Versus the Lattice
After mentioning some of the difficulties arising in lattice gauge theory
from chiral symmetry, I discuss one of the recent attempts to resolve these
issues using fermionic surface states in an extra space-time dimension. This
picture can be understood in terms of end states on a simple ladder molecule.Comment: Talk at the meeting "Computer simulations studies in condensed matter
physics XIV" Athens, Georgia, Feb. 19-24, 2001. 14 page
Ambiguities in the up quark mass
It has long been known that no physical singularity is encountered as up
quark mass is adjusted from small positive to negative values as long as all
other quarks remain massive. This is tied to an additive ambiguity in the
definition of the quark mass. This calls into question the acceptability of
attempts to solve the strong CP problem via a vanishing mass for the lightest
quark.Comment: 9 pages, 1 figure. Revision as will appear in Physical Review
Letters. Simplified renormalization group discussion and title change
requested by PR
Specific Heat Exponent for the 3-d Ising Model from a 24-th Order High Temperature Series
We compute high temperature expansions of the 3-d Ising model using a
recursive transfer-matrix algorithm and extend the expansion of the free energy
to 24th order. Using ID-Pade and ratio methods, we extract the critical
exponent of the specific heat to be alpha=0.104(4).Comment: 10 pages, LaTeX with 5 eps-figures using epsf.sty, IASSNS-93/83 and
WUB-93-4
Off-diagonal Gluon Mass Generation and Infrared Abelian Dominance in Maximally Abelian Gauge in SU(3) Lattice QCD
In SU(3) lattice QCD formalism, we propose a method to extract gauge fields
from link-variables analytically. With this method, we perform the first study
on effective mass generation of off-diagonal gluons and infrared Abelian
dominance in the maximally Abelian (MA) gauge in the SU(3) case. Using SU(3)
lattice QCD, we investigate the propagator and the effective mass of the gluon
fields in the MA gauge with U(1)_3 \timesU(1)_8 Landau gauge fixing. The
Monte Carlo simulation is performed on at =5.7, 5.8 and 6.0 at
the quenched level. The off-diagonal gluons behave as massive vector bosons
with the approximate effective mass in the region of fm, and the propagation is
limited within a short range, while the propagation of diagonal gluons remains
even in a large range. In this way, infrared Abelian dominance is shown in
terms of short-range propagation of off-diagonal gluons. Furthermore, we
investigate the functional form of the off-diagonal gluon propagator. The
functional form is well described by the four-dimensional Euclidean Yukawa-type
function with
for fm. This also indicates that the spectral function of
off-diagonal gluons has the negative-value region
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