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hep-lat/9211064
|
Fermion mass in the Wilson-Yukawa approach for chiral Yukawa theory
|
We consider a modification of the Wilson-Yukawa model to overcome its
difficulty that the fermion mass is not proportional to the Higgs vacuum
expectation value. In the modification scalar and fermionic regulator fields
are introduced so that all the physical fermion fields possess shift symmetry
when the Yukawa coupling vanishes. With the fermionic hopping parameter
expansion it is shown that the fermion mass is proportional to the Higgs vacuum
expectation value and that the coupling of fermion to the external gauge field
can be chiral if the hopping parameter of the scalar regulator field is taken
to the critical value.
| 1992-11-27
| 2015-06-25
|
[
"hep-lat"
] |
Sinya Aoki and Yoshio Kikukawa
|
hep-lat/9211065
|
The S, U and \Delta\rho parameters in the Zaragoza proposal for lattice
chiral gauge fermions
|
Using the Zaragoza proposal for lattice chiral gauge fermions, the S, U and
\Delta\rho parameters have been calculated at one loop. It is shown that the
continuum values for these quantities can be reproduced without requiring
explicit fine tuning of counterterms. Furthermore, fermion fields doubling is
not necessary. To the best of our knowledge, the Zaragoza proposal is the only
scheme which has these properties. A necessary (although not sufficient)
symmetry is found to support the calculations. Previous results for some of
these parameters in other lattice chiral regularizations are revisited in the
light of this symmetry.
| 1992-11-27
| 2010-03-19
|
[
"hep-lat"
] |
Jose Luis Alonso, Philippe Boucaud, Jose Luis Cortes, Felipe Lesmes,
and Elena Rivas
|
hep-lat/9211063
|
Enumeration of self avoiding trails on a square lattice using a transfer
matrix technique
|
We describe a new algebraic technique, utilising transfer matrices, for
enumerating self-avoiding lattice trails on the square lattice. We have
enumerated trails to 31 steps, and find increased evidence that trails are in
the self-avoiding walk universality class. Assuming that trails behave like $A
\lambda ^n n^{11 \over 32}$, we find $\lambda = 2.72062 \pm 0.000006$ and $A =
1.272 \pm 0.002$.
| 1992-11-27
| 2009-10-22
|
[
"hep-lat"
] |
A R Conway and A J Guttmann
|
hep-lat/9211061
|
No strong coupling regime in the fermion-Higgs sector of the standard
model
|
We present results for the renormalized quartic self-coupling $\lm_R$ and the
renormalized Yukawa coupling $y_R$ in a fermion-Higgs model with two SU(2)
doublets, indicating that these couplings are not very strong.
| 1992-11-26
| 2009-10-22
|
[
"hep-lat"
] |
Wolfgang Bock, Christoph Frick, Jan Smit and Jeroen C. Vink
|
hep-lat/9211060
|
Staggered fermion approach to chiral gauge theories on the lattice
|
The staggered fermion approach to build models with chiral fermions is
briefly reviewed. The method is tested in a U(1) model with axial vector
coupling in two and four dimensions.
| 1992-11-25
| 2009-10-22
|
[
"hep-lat"
] |
W. Bock, J. Smit and J.C. Vink
|
hep-lat/9211059
|
Finite temperature QED3 with light fermions
|
Non-compact QED3 is simulated both in the quenched and unquenched cases. In
particular, we investigate the restoration of chiral symmetry at finite
temperature. We also compute the zero temperature spectrum of the theory,
including (in the quenched case) the dynamical fermion mass. From these two set
of data, one can obtain estimates for the ratio of the mass gap to the critical
temperature, of particular interest for applications to high-Tc
superconductivity.
| 1992-11-25
| 2009-10-22
|
[
"hep-lat"
] |
J.B. Kogut and J.-F. Lagae
|
hep-lat/9211058
|
Chiral Corrections to Lattice Calculations of Charge Radii
|
Logarithmic divergences in pion and proton charge radii associated with
chiral loops are investigated to assess systematic uncertainties in current
lattice determinations of charge radii. The chiral corrections offer a possible
solution to the long standing problem of why present lattice calculations yield
proton and pion radii which are similar in size.
| 1992-11-24
| 2009-10-22
|
[
"hep-lat",
"hep-ph",
"nucl-th"
] |
Derek B. Leinweber and Thomas D. Cohen
|
hep-lat/9211057
|
Meson Form-factors and Wave-functions with Wilson fermions
|
Results for semi-leptonic form-factors for processes like $D \to K l \nu$ and
the Bethe-Salpeter amplitudes (BSA) for pion and rho mesons are presented. The
form-factor data is consistent with previous calculations. We find that the
long distance fall-off of BSA for both $\pi$ and $\rho$ is very well fit by an
exponential, but surprisingly the effective mass governing this fall-off is
lighter than the pion's. Lastly, by studying the dependence of $\rho$
polarization on separation direction we show that there is a measureable $l=2$
state in addition to $l=0$ in the BSA for the rho. (Talk presented by R. Gupta
at LATTICE92. Latex needs macro package espcrc2.sty)
| 1992-11-24
| 2009-10-22
|
[
"hep-lat"
] |
R. Gupta, D. Daniel, J. Grandy
|
hep-lat/9211055
|
Finite-Size Scaling on the Ising Coexistence Line
|
We study the finite-size scaling of moments of the magnetization in the
low-temperature phase of the two-dimensional Ising model.
| 1992-11-23
| 2009-10-22
|
[
"hep-lat"
] |
S. Gupta and A. Irbaeck
|
hep-lat/9211056
|
Study of the complex fermion determinant in a $\rm U(1)_L \otimes
U(1)_R$ symmetric Yukawa model
|
Lattice theories that contain chiral multiplets of fermions can have complex
fermion determinants. This is for example the case for the $\rm U(1)_L \otimes
U(1)_R$ symmetric Yukawa model with mirror fermions, if the number of
generations of fermions and mirror fermions is odd. Whether a numerical
simulation of such a model is possible depends on the magnitude of fluctuations
of the complex phase factor of the fermion determinant. We investigate the
fermion determinant of the U(1) Yukawa model with mirror fermions for a
physically relevant choice of parameters. The argument of the complex phase
turns out to fluctuate only very little and is at most of the order of $2 \cdot
10^{-3}$.
| 1992-11-23
| 2010-12-23
|
[
"hep-lat"
] |
Gernot Muenster and Markus Plagge
|
hep-lat/9211054
|
Glueball wavefunctions
|
We measure Coulomb-gauge wavefunctions of the scalar and tensor glueballs in
SU(2) Yang-Mills. The problem of contamination by flux states is discussed, and
a new analysis method described. The large size of the tensor glueball is
confirmed. Preliminary results in the deconfined phase show no significant
changes.
| 1992-11-22
| 2009-10-22
|
[
"hep-lat"
] |
Philippe de Forcrand and Keh-Fei Liu
|
hep-lat/9211053
|
High precision single-cluster Monte Carlo measurement of the critical
exponents of the classical 3D Heisenberg model
|
We report measurements of the critical exponents of the classical
three-dimensional Heisenberg model on simple cubic lattices of size $L^3$ with
$L$ = 12, 16, 20, 24, 32, 40, and 48. The data was obtained from a few long
single-cluster Monte Carlo simulations near the phase transition. We compute
high precision estimates of the critical coupling $K_c$, Binder's parameter
$U^* and the critical exponents $\nu,\beta / \nu, \eta$, and $\alpha / \nu$,
using extensively histogram reweighting and optimization techniques that allow
us to keep control over the statistical errors. Measurements of the
autocorrelation time show the expected reduction of critical slowing down at
the phase transition as compared to local update algorithms. This allows
simulations on significantly larger lattices than in previous studies and
consequently a better control over systematic errors in finite-size scaling
analyses.
| 1992-11-19
| 2009-10-22
|
[
"hep-lat"
] |
C. Holm, and W. Janke
|
hep-lat/9211051
|
Infinite Volume, Continuum Limit of Valence Approximation Hadron Masses
|
We obtain estimates of several hadron mass ratios, for Wilson quarks in the
valence (quenched) approximation, extrapolated to physical quark mass, infinite
volume and zero lattice spacing.
| 1992-11-19
| 2009-10-22
|
[
"hep-lat",
"hep-ph"
] |
F. Butler, H. Chen, A. Vaccarino, J. Sexton, and D. Weingarten
|
hep-lat/9211052
|
Yet another way to obtain low temperature expansions for discrete spin
systems
|
I present a modification of the shadow-lattice technique, which allows one to
derive low temperature series for discrete spin models to high orders. Results
are given for the 3-d Ising model up to 64 excited bonds, for the 4-d Ising
model up to 96 excited bonds and the 3-d Potts model up to 56 excited bonds.
| 1992-11-19
| 2009-10-22
|
[
"hep-lat"
] |
C. Vohwinkel
|
hep-lat/9211050
|
The Mechanism of Complex Langevin Simulations
|
We discuss conditions under which expectation values computed from a complex
Langevin process $Z$ will converge to integral averages over a given complex
valued weight function. The difficulties in proving a general result are
pointed out. For complex valued polynomial actions, it is shown that for a
process converging to a strongly stationary process one gets the correct answer
for averages of polynomials if $c_{\tau}(k) \equiv E(e^{ikZ(\tau)}) $ satisfies
certain conditions. If these conditions are not satisfied, then the stochastic
process is not necessarily described by a complex Fokker Planck equation. The
result is illustrated with the exactly solvable complex frequency harmonic
oscillator.
| 1992-11-18
| 2009-10-22
|
[
"hep-lat"
] |
H. Gausterer and Sean Lee
|
hep-lat/9211048
|
Quenched Lattice Results for $f_B$ and $f_D$
|
We have computed the decay constants for the $B$ and $D$ mesons, using
quenched lattices at $\beta=6.3$, by interpolating between the static
approximation of Eichten and the conventional (``heavy'' Wilson fermion)
method. A more careful treatment of the static result using better sources with
longer time-displacements and a modification to the Wilson quark normalization
to correct approximately for lattice effects in the large-$am$ regime have led
to the elimination of the large discrepancy between the two methods which had
been previously observed. We report final results, with estimates of various
systematic errors.
| 1992-11-18
| 2009-10-22
|
[
"hep-lat"
] |
Claude Bernard, James Labrenz and Amarjit Soni
|
hep-lat/9211047
|
The Loop-Cluster Algorithm for the Case of the 6 Vertex Model
|
We present the loop algorithm, a new type of cluster algorithm that we
recently introduced for the F model. Using the framework of Kandel and Domany,
we show how to GENERALIZE the algorithm to the arrow flip symmetric 6 vertex
model. We propose the principle of least possible freezing as the guide to
choosing the values of free parameters in the algorithm. Finally, we briefly
discuss the application of our algorithm to simulations of quantum spin
systems. In particular, all necessary information is provided for the
simulation of spin $\half$ Heisenberg and $xxz$ models.
| 1992-11-18
| 2007-05-23
|
[
"hep-lat",
"cond-mat"
] |
H.G. Evertz and M. Marcu
|
hep-lat/9211049
|
Multicanonical Cluster Algorithm
|
In this talk I present a multicanonical hybrid-like two-step algorithm, which
consists of a microcanonical spin system update with demons, and a
multicanonical demon refresh. The demons act as a buffer between the
multicanonical heat bath and the spin system, allowing for a large variety of
update schemes. In this work the cluster algorithm is demonstrated with the
2-dimensional 7-state Potts model, using volumes up to $128^2$.
| 1992-11-18
| 2009-10-22
|
[
"hep-lat",
"cond-mat"
] |
K. Rummukainen
|
hep-lat/9211046
|
The Charmonium Spectrum on the Lattice: A Status Report
|
We present our most recent results on the charmonium spectrum using
relativistic Wilson fermions. We study the dependence of the spectrum on the
charm quark mass and the Wohlert-Sheikholeslami improvement term.
| 1992-11-17
| 2010-11-19
|
[
"hep-lat",
"hep-ph"
] |
Aida X. El-Khadra
|
hep-lat/9211045
|
Charmed Meson Spectroscopy and Matrix Elements with an O(a)-Improved
Clover Fermion Action
|
We present preliminary results for the spectrum and decay matrix elements for
heavy-light and heavy-heavy mesons, obtained on the 64-node Meiko Computing
Surface at the University of Edinburgh. Quark propagators are computed with an
O(a)-improved fermion action on 24^3x48 lattices at beta = 6.2, using three
values of the quark mass up to around the strange quark mass, and four values
of the quark mass in the region of the charm quark mass. We compare results for
the hyperfine splitting in charmonium with those obtained using the
conventional Wilson fermion action and find that the splitting is 1.83(15)
times larger with the improved action. Our measurements of f_B indicate
non-scaling corrections of the order of 20% to the Heavy Quark Effective Theory
expectation. A comparison is made with results obtained on 16^3x48 lattices at
beta = 6.0.
| 1992-11-17
| 2019-06-05
|
[
"hep-lat"
] |
UKQCD Collaboration, presented by David Richards
|
hep-lat/9211044
|
Gravitational Action Versus Entropy on Simplicial Lattices in Four
Dimensions
|
We investigate quantum gravity on simplicial lattices using Regge calculus
with special emphasize on the problem of the unbounded action. The role of the
entropy for the path integral is discussed in detail. Our numerical results
show further evidence for the existence of an entropy dominated region with
well defined expectation values even for unbounded action. Analyses are
performed both for the standard regular triangulation of the 4-torus and for
irregularly triangulated lattices obtained by insertion of vertices using
barycentric subdivision.
| 1992-11-17
| 2009-10-22
|
[
"hep-lat"
] |
W. Beirl, E. Gerstenmayer, H. Markum and J. Riedler
|
hep-lat/9211041
|
Results in the static approximation
|
We present a comprehensive study of finite volume and lattice spacing effects
on observables calculated in the static approximation. Ground state projection
using smearing techniques is studied at $\beta=6.26$. We give high statics
results for the pseudoscalar decay constant after extrapolating to the chiral
and continuum limit. In addition results for mass splittings and the distance
of string breaking in the $Q\bar{Q}$ potential are presented.
| 1992-11-16
| 2009-10-22
|
[
"hep-lat"
] |
C. Alexandrou, S. Guesken, F. Jegerlehner, K. Schilling, R. Sommer
|
hep-lat/9211043
|
The Charm Quark on the Lattice
|
We formulate lattice fermions in a way that encompasses Wilson fermions as
well as the static and non-relativistic approximations. In particular, we treat
$m_qa$ systematically ($m_q$ is the fermion mass) showing how to understand the
Wilson action as an effective action for systems with $\vek{p}\ll m_q$. The
results show how to extract matrix elements and the spectrum from simulations
with $m_qa\approx1$, which is relevant for the charm quark.
| 1992-11-16
| 2009-10-22
|
[
"hep-lat"
] |
Andreas S. Kronfeld
|
hep-lat/9211042
|
The Static Approximation of Heavy-Light Quark-Systems - A Systematic
Lattice Study
|
We present a study of {\it finite} $a$ and {\it volume} effects of the
leptonic decay constant $f$ of heavy pseudoscalar mesons in the static
approximation. This study is performed on a number of lattices at $\beta=$
5.74,~6.0 and 6.26 covering sizes from about 0.7~$fm$ to 2~$fm$. We confirm
that beyond 1.5~$fm$ the volume dependence is negligible. By carefully
analysing results obtained using different trial wave functions for the heavy
meson we find no dependence on the smearing. We also give results for the mass
difference of the scalar - pseudoscalar and the $\Lambda _{b}$ - pseudoscalar.
Using the mass of the pseudoscalar meson we estimate the distance of string
breaking in the static quark potential.
| 1992-11-16
| 2009-10-22
|
[
"hep-lat"
] |
C. Alexandrou, S. Guesken, F. Jegerlehner, K. Schilling, R. Sommer
|
hep-lat/9211038
|
The Spin Content of the Nucleon
|
The fraction of the nucleon spin that is carried by the quarks, $\Delta
\Sigma$, is computed in lattice QCD with dynamical staggered fermions. We
obtain the value $\Delta \Sigma = 0.18 \pm 0.02$.
| 1992-11-13
| 2009-10-22
|
[
"hep-lat"
] |
R. Altmeyer, M. G\"ockeler, R. Horsley, E. Laermann and G. Schierholz
|
hep-lat/9211040
|
Quenched Light Hadron Spectroscopy: Comparing the Wilson and
O(a)-Improved Fermion Actions
|
We have studied the light hadron spectrum and decay constants for quenched
QCD at beta=6.2 on a 24^3x48 lattice. We compare the results obtained using a
nearest-neighbour O(a)-improved ("clover") fermion action with those obtained
using the standard Wilson fermion action on the same gauge configurations. For
pseudoscalar meson masses in the range 330-800 MeV, we find no significant
difference between the results for the two actions. The scales obtained from
the string tension and mesonic sector are consistent, but higher than those
derived from baryon masses. The ratio of the pseudoscalar decay constant to the
vector meson mass is roughly independent of quark mass as observed
experimentally.
| 1992-11-13
| 2019-06-05
|
[
"hep-lat"
] |
UKQCD Collaboration, presented by Alan D. Simpson
|
hep-lat/9211037
|
Improved Langevin Methods for Spin Systems
|
We investigate methods for variance reduction and the elimination of
systematic error in a Fourier accelerated Langevin scheme for general spin
models. We present results for the $SU(3)\times SU(3)/SU(3)$ model in
two-dimensions that are consistent wit h those from multi-grid methods. We
argue that the timing for the Langevin method makes it comparable to multi-grid
for a given level of error.
| 1992-11-13
| 2009-10-22
|
[
"hep-lat"
] |
I T Drummond and R R Horgan
|
hep-lat/9211039
|
Gauge Invariant Smearing and Matrix Correlators using Wilson Fermions at
beta=6.2
|
We present an investigation of gauge invariant smearing for Wilson fermions
on a $24^3 \times 48$ lattice at $\beta = 6.2$. We demonstrate a smearing
algorithm that allows a substantial improvement in the determination of the
baryon spectrum obtained using propagators smeared at both source and sink, at
only a small computational cost. We investigate the matrix of correlators
constructed from local and smeared operators, and are able to expose excited
states of both the mesons and baryons.
| 1992-11-13
| 2019-08-27
|
[
"hep-lat"
] |
UKQCD Collaboration (presented by Sara Collins)
|
hep-lat/9211036
|
Baryon Density Correlations in the Quark Plasma, MIMD Lattice
Calculation
|
As part of an ongoing effort to characterize the high temperature phase of
QCD, we measure the quark baryon density in the vicinity of a fixed test quark
and compare it with similar measurements at low temperature and at the
crossover temperature. Such an observable has also been studied by the Vienna
group. We find an extremely weak correlation at high temperature, suggesting
that small color singlet clusters are unimportant in the thermal ensemble. We
also find that at T = 0.75 T_c the induced quark number shows a surprisingly
large component attributable to baryonic screening. A simulation of a simple
flux tube model produces results that suggest a plausible scenario: As the
crossover temperature is approached from below, baryonic states proliferate.
Above the crossover temperature the mean size of color singlet clusters grows
explosively, resulting in an effective electrostatic deconfinement.
| 1992-11-12
| 2008-11-26
|
[
"hep-lat"
] |
C. Bernard, T. A. DeGrand, C. DeTar, S. Gottlieb, A. Krasnitz, R. L.
Sugar and D. Toussaint (MILC Collaboration)
|
hep-lat/9211033
|
Non-Relativistic QCD for Heavy Quark Systems
|
We employ a nonrelativistic version of QCD (NRQCD) to study heavy
quark-antiquark bound states in the lowest approximation without fine
structure. We use gluon configurations on a 16^3 by 48 lattice at beta=6.2 from
the UKQCD collaboration. For quark masses in the vicinity of the b we obtain
bound state masses for S, P and both types of D wave. We also detect signals
for two types of hybrids (quark,antiquark,gluon states). The results are
sufficiently accurate to confirm that the values of the D wave mass from both
lattice D waves coincide indicating that the cubical invariance of the lattice
is restored to full rotational invariance at large distance.
Our results also show that the S-P splitting is indeed insensitive to
variations in the bare quark mass from Ma=1.0 to Ma=1.9.
| 1992-11-12
| 2010-11-01
|
[
"hep-lat"
] |
S.Catterall, F.Devlin, I.Drummond, R.Horgan, A. Simpson
|
hep-lat/9211034
|
Blockspin Scheme and Cluster Algorithm for Quantum Spin Systems
|
We present a numerical study using a cluster algorithm for the 1-d $S=1/2$
quantum Heisenberg models. The dynamical critical exponent for
anti-ferromagnetic chains is $z=0.0(1)$ such that critical slowing down is
eliminated.
| 1992-11-12
| 2007-05-23
|
[
"hep-lat"
] |
He-Ping Ying and Uwe-Jens Wiese (Bern University)
|
hep-lat/9211035
|
Quark Confinement in Multi-Flavor Quantum Chromodynamics
|
It is investigated how quark confinement depends on the number of flavors,
$N_f$, in QCD on the lattice with Wilson quarks. We strengthen and extend the
conclusion reported at {\it Lattice 91}: (1) For $N_f \le 6$ the finite
temperature deconfining transition/crossover line crosses the chiral limit at
finite $\beta$. We identify the crossing point for $N_f=2$ and 6 on a $T=4$
lattice, where $T$ is the lattice size in the temporal direction. We find the
phase transition at the crossing point is continuous for $N_f=2$, while it is
of first order for $N_f=6$. (2) For $N_f \ge 7$, the $T$-independent
deconfining transition observed at $\beta=0$ extends up to $\beta=4.5$ with the
critical quark mass $m_{\rm quark} = O(a^{-1})$, where $a$ is the lattice
spacing.
| 1992-11-12
| 2009-10-22
|
[
"hep-lat"
] |
Y. Iwasaki, K. Kanaya, S. Sakai, and T. Yoshie
|
hep-lat/9211030
|
A method for putting chiral fermions on the lattice
|
We describe a method to put chiral gauge theories on the lattice. Our method
makes heavy use of the effective action for chiral fermions in the continuum,
which is in general complex. As an example we discuss the chiral Schwinger
model.
| 1992-11-11
| 2014-11-17
|
[
"hep-lat"
] |
M. Goeckeler and G. Schierholz
|
hep-lat/9211028
|
Anomalous Fermion Number Non-Conservation on the Lattice
|
The anomaly for the fermion number current is calculated on the lattice in a
simple prototype model with an even number of fermion doublets.
| 1992-11-11
| 2009-10-22
|
[
"hep-lat"
] |
Istvan Montvay (CERN, Geneva, Switzerland)
|
hep-lat/9211031
|
Multigrid meets Neural Nets
|
We present evidence that multigrid (MG) works for wave equations in
disordered systems, e.g. in the presence of gauge fields, no matter how strong
the disorder. We introduce a "neural computations" point of view into large
scale simulations: First, the system must learn how to do the simulations
efficiently, then do the simulation (fast). The method can also be used to
provide smooth interpolation kernels which are needed in multigrid Monte Carlo
updates.
| 1992-11-11
| 2009-10-22
|
[
"hep-lat"
] |
M. Baeker, G. Mack and M. Speh
|
hep-lat/9211027
|
Contamination of Excited States in Quenched QCD Hadron Propagators
|
Quenched QCD hadron spectrum is calculated with Wilson's quark action at
$\beta=5.85$ and 6.0 on a $24^3 \times 54$ lattice. We discuss the problem of
whether we have extracted the mass of the ground state at these $\beta$'s
without contamination of the excited states. We show that the masses of the
first excited states turn out to be consistent with experiment when we are able
to obtain the propagators up to the large time slice region where the
propagators take the asymptotic forms of the ground states.
| 1992-11-11
| 2009-10-22
|
[
"hep-lat"
] |
QCDPAX collaboration: Y.Iwasaki, K.Kanaya, S.Sakai, T.Yoshie,
T.Hoshino, T.Shirakawa and Y.Oyanagi
|
hep-lat/9211026
|
Fermion spectrum in the quenched U(1) chiral Wilson-Yukawa model
|
Nature of charged fermion state is investigated in the quenched U(1) chiral
Wilson-Yukawa model. Fitting the charged fermion propagator with a single
hyperbolic cosine does not yield reliable result. On the other hand the
behaviour of the propagator including large lattice size dependence is well
described by the large Wilson-Yukawa coupling expansion, providing strong
evidence that no charged state exists as an asymptotic particle in this model.
| 1992-11-11
| 2009-10-22
|
[
"hep-lat"
] |
S. Aoki, H. Hirose and Y. Kikukawa
|
hep-lat/9211032
|
Decoupling of Photon Propagator in Compact QED
|
In compact QED$_{2+1}$ quantum monopole fluctuations induce confinement by
expelling electric flux in a dual Meissner effect. Guided by Landau-Ginzburg
theory, one might guess that the inverse London penetration depth
$\lambda^{-1}$---the only physical mass scale---equals the photon propagator
mass pole $M_\gamma$. I show this is not true. Indeed, in the Villain
approximation the monopole part of the partition function factorizes from the
photon part, whose dynamical variables are Dirac strings. Since Dirac strings
are gauge-variant structures, I conclude that $M_\gamma$ is physically
irrelevant: it is not a blood relative of $\lambda$ or any other quantity in
the gauge-invariant sector. This result is confirmed by numerical simulations
in the full theory, where $M_\gamma$ is not sensitive to monopole prohibition
but essentially vanishes if Dirac strings are prohibited.
| 1992-11-11
| 2009-10-22
|
[
"hep-lat"
] |
Ken Yee
|
hep-lat/9211029
|
Unstable particles in finite volume: The broken phase of the $4$-d
$O(4)$ non-linear $\sigma$-model
|
According to a proposal of L\"uscher it is possible to determine elastic
scattering phases in infinite volume from the energy spectrum of two-particle
states in a periodic box.
We demonstrate the applicability of this method in the broken phase of the
4-dimensional $O(4)$ non-linear $\sigma$-model in a Monte-Carlo study on finite
lattices.
This non-perturbative approach also permits the study of unstable particles,
the $\sg$-particle in our case. We observe the $\sg$-resonance and extract its
mass and its width.
| 1992-11-11
| 2009-10-22
|
[
"hep-lat"
] |
Frank Zimmermann, J\"org Westphalen, Meinulf G\"ockeler and Hans A.
Kastrup
|
hep-lat/9211022
|
How Do Fermions Behave on a Random Lattice?
|
Comparing random lattice, naive and Wilson fermions in two dimensional
abelian background gauge field, we show that the doublers suppressed in the
free field case are revived for random lattices in the continuum limit unless
gauge interactions are implemented in a non--invariant way.
| 1992-11-10
| 2009-10-22
|
[
"hep-lat",
"hep-th"
] |
C J Griffin and T D Kieu
|
hep-lat/9211023
|
Quantum-Gravity Path-Integrals on Simplicial Lattices
|
Euclidean quantum-gravity path-integrals are investigated within Regge
calculus by computer simulations. The domain of integration is restricted by
introducing a lower limit for the fatness of each simplex. We use the standard
hypercubic triangulation of the 4-torus and irregularly triangulated lattices
obtained by inserting a small number of vertices using barycentric subdivision.
For limited fatness we find an entropy dominated phase with small negative
curvature both for the regular and the irregular triangulation.
| 1992-11-10
| 2009-10-22
|
[
"hep-lat"
] |
W. Beirl, E. Gerstenmayer, H. Markum
|
hep-lat/9211024
|
Strings with Extrinsic Curvature: An Analysis of the Crossover Regime
|
We present the results of a set of Monte Carlo simulations of Dynamically
Triangulated Random Surfaces embedded in three dimensions with an extrinsic
curvature dependent action. We analyze several observables in the crossover
regime and discuss whether or not our observations are indicative of the
presence of a phase transition.
| 1992-11-10
| 2009-10-22
|
[
"hep-lat"
] |
Mark Bowick, Paul Coddington, Leping Han, Geoffrey Harris and Enzo
Marinari
|
hep-lat/9211025
|
Hamiltonian lattice gauge theory: wavefunctions on large lattices
|
We discuss an algorithm for the approximate solution of Schrodinger's
equation for lattice gauge theory, using lattice SU(3) as an example. A basis
is generated by repeatedly applying an effective Hamiltonian to a ``starting
state.'' The resulting basis has a cluster decomposition and long-range
correlations. One such basis has about 10^4 states on a 10X10X10 lattice. The
Hamiltonian matrix on the basis is sparse, and the elements can be calculated
rapidly. The lowest eigenstates of the system are readily calculable.
| 1992-11-10
| 2016-08-31
|
[
"hep-lat"
] |
J. B. Bronzan
|
hep-lat/9211021
|
A streamlined method for chiral fermions on the lattice
|
We discuss the use of renormalization counterterms to restore the chiral
gauge symmetry in a lattice theory of Wilson fermions. We show that a large
class of counterterms can be implemented automatically by making a simple
modification to the fermion determinant.
| 1992-11-09
| 2014-11-17
|
[
"hep-lat"
] |
Geoffrey T. Bodwin, Eve V. Kovacs
|
hep-lat/9211020
|
The Gluon Propagator in Momentum Space
|
We give preliminary numerical results for the gluon propagator evaluated both
in coordinate and momentum space on a 16^3X40 quenched lattice at beta=6.0. Our
findings are compared with earlier results in the literature at zero momentum.
In addition, by considering nonzero momenta we attempt to extract the form of
the propagator and compare it to continuum predictions formulated by Gribov and
others. latex, file espcrc2.sty needed (appended at the end: search for
espcrc2.sty).
| 1992-11-09
| 2009-10-22
|
[
"hep-lat"
] |
C. Bernard, C. Parrinello and A. Soni
|
hep-lat/9211019
|
Lattice Calculation of Point-to-Point Hadron Current Correlation
|
Point-to-point correlation functions of hadron currents in the QCD vacuum are
calculated on a lattice and analyzed using dispersion relations, providing
physical information down to small spatial separations. Qualitative agreement
with phenomenological results is obtained in channels for which experimental
data are available, and these correlation functions are shown to be useful in
exploring approximations based on sum rules and interacting instantons.
| 1992-11-09
| 2008-11-26
|
[
"hep-lat"
] |
M.-C. Chu, J. M. Grandy, S. Huang and J. W. Negele
|
hep-lat/9211018
|
Gribov Copies and Other Gauge Fixing Beasties on the Lattice
|
Write-up for Lattice'92, held in Amsterdam. preprint LTH 291.
Comes with 6 PostScript figures and 1 sty-file. We study the nature of gauge
fixing ambiguities in two dimensional gauge theories. We find that these
ambiguities can be related to the asociated spin model. They can be eliminated
by means of a (multigrid) annealing algorithm.
| 1992-11-07
| 2009-10-22
|
[
"hep-lat"
] |
Arjan Hulsebos
|
hep-lat/9211017
|
The Quenched Approximation in Health and in Sickness
|
We present results for physical quantities computed in quenched chiral
perturbation theory and compare them with the corresponding unquenched
expressions. We also point out an apparent theoretical problem of the quenched
approximation. latex, file espcrc2.sty needed (appended at the end: search for
espcrc2.sty).
| 1992-11-06
| 2009-10-22
|
[
"hep-lat"
] |
Claude Bernard and Maarten Golterman
|
hep-lat/9211016
|
Fermion induced SU$(N)$ Yang-Mills Theory
|
We investigate the gauge interaction induced by heavy fermions using both
dimensional and lattice regularization. We study the condition under which
heavy fermions induce a continuum gauge theory.
| 1992-11-05
| 2009-10-22
|
[
"hep-lat"
] |
Anna Hasenfratz
|
hep-lat/9211015
|
Three-Loop Results on the Lattice
|
We present some new three-loop results in lattice gauge theories, for the
Free Energy and for the Topological Susceptibility. These results are an
outcome of a scheme which we are developing (using a symbolic manipulation
language), for the analytic computation of renormalization functions on the
lattice.
| 1992-11-05
| 2009-10-22
|
[
"hep-lat"
] |
B. Alles, M. Campostrini, A. Feo and H. Panagopoulos
|
hep-lat/9211013
|
Random Walks with Long-Range Self-Repulsion on Proper Time
|
We introduce a model of self-repelling random walks where the short-range
interaction between two elements of the chain decreases as a power of the
difference in proper time. Analytic results on the exponent $\nu$ are obtained.
They are in good agreement with Monte Carlo simulations in two dimensions. A
numerical study of the scaling functions and of the efficiency of the algorithm
is also presented.
| 1992-11-05
| 2015-06-25
|
[
"hep-lat"
] |
S. Caracciolo, G. Parisi and A. Pelissetto
|
hep-lat/9211014
|
Observation of FSS for a First Order Phase Transition
|
We present the results of a multicanonical simulation of the q=20 2-d Potts
model in the transition region. This is a very strong first order phase
transition. We observe, for the first time, the asymptotic finite size scaling
behavior predicted by Borgs and Koteck\'y close to a first order phase
transition point.
| 1992-11-05
| 2009-10-22
|
[
"hep-lat",
"cond-mat"
] |
A. Billoire, T. Neuhaus and B. Berg
|
hep-lat/9211012
|
Lattice Analysis of Two-Point Hadronic Correlators in the QCD Vacuum
|
Results from the first lattice QCD analysis of vacuum correlators of local
hadronic currents using dispersion relations are presented. We have explored
the vector, pseudoscalar, axial, and scalar meson channels, and the proton-like
and delta-like baryon channels. The lattice results are shown to agree
qualitatively with experimental results in channels where experimental data
exist, and shed insight into interacting instanton approximations and sum rule
calculations in the other channels.
3 figures included (as PostScript files): pi.ps, nd.ps, va.ps : Search for
%%% to retrieve the files. Latex file, needs espcrc2.sty (Search for %%%).
| 1992-11-05
| 2010-05-27
|
[
"hep-lat"
] |
M.-C. Chu, J. M. Grandy, S. Huang, and J. W. Negele
|
hep-lat/9211011
|
Lattice Charge Overlap and the Elastic Limit
|
The results of a lattice simulation of time-separated charge overlap for the
charged pion are discussed. The expected result $\sim {\rm exp}[-(E_q -
m_{\pi})t\,]$ for large charge density overlap time separations, $t$, is
clearly visible in the Fourier transform, indicating that the elastic limit can
be achieved at low to medium momentum values on present-sized lattices. The
implications of this result for direct lattice simulations of hadron structure
functions are discussed and a brief presentation of the lattice formalism is
given.
| 1992-11-04
| 2009-10-22
|
[
"hep-lat"
] |
Walter Wilcox
|
hep-lat/9211010
|
Surface Tension, Surface Stiffness, and Surface Width of the
3-dimensional Ising Model on a Cubic Lattice
|
We compute properties of the interface of the 3-dimensional Ising model for a
wide range of temperatures and for interface extensions up to 64 by 64. The
interface tension sigma is obtained by integrating the surface energy density
over the inverse temperature beta. The surface stiffness coefficient kappa is
determined. We also study universal quantities like xi^2 sigma and xi^2 kappa.
The behavior of the interfacial width on lattices up to 512 times 512 times 27
is also investigated.
| 1992-11-04
| 2009-10-22
|
[
"hep-lat"
] |
Martin Hasenbusch and Klaus Pinn
|
hep-lat/9211008
|
Multigrid for propagators of staggered fermions in four-dimensional
$SU(2)$ gauge fields
|
Multigrid (MG) methods for the computation of propagators of staggered
fermions in non-Abelian gauge fields are discussed. MG could work in principle
in arbitrarily disordered systems. The practical variational MG methods tested
so far with a ``Laplacian choice'' for the restriction operator are not
competitive with the conjugate gradient algorithm on lattices up to $18^4$.
Numerical results are presented for propagators in $SU(2)$ gauge fields.
| 1992-11-04
| 2016-08-31
|
[
"hep-lat"
] |
Thomas Kalkreuter
|
hep-lat/9211009
|
The confined-deconfined interface tension, wetting, and the spectrum of
the transfer matrix
|
The reduced tension $\sigma_{cd}$ of the interface between the confined and
the deconfined phase of $SU(3)$ pure gauge theory is determined from numerical
simulations of the first transfer matrix eigenvalues. At $T_c = 1/L_t$ we find
$\sigma_{cd} = 0.139(4) T_c^2$ for $L_t = 2$. The interfaces show universal
behavior because the deconfined-deconfined interfaces are completely wet by the
confined phase. The critical exponents of complete wetting follow from the
analytic interface solutions of a $\Z(3)$-symmetric $\Phi^4$ model in three
dimensions. We find numerical evidence that the confined-deconfined interface
is rough.
| 1992-11-04
| 2009-10-22
|
[
"hep-lat"
] |
B. Grossmann, M. L. Laursen, T. Trappenberg and U.-J. Wiese
|
hep-lat/9211006
|
A Gauge-fixed Hamiltonian for Lattice QCD
|
We study the gauge fixing of lattice QCD in 2+1 dimensions, in the
Hamiltonian formulation. The technique easily generalizes to other theories and
dimensions. The Hamiltonian is rewritten in terms of variables which are gauge
invariant except under a single global transformation. This paper extends
previous work, involving only pure gauge theories, to include matter fields.
| 1992-11-03
| 2009-10-22
|
[
"hep-lat"
] |
J. B. Bronzan and Timothy E. Vaughan
|
hep-lat/9211007
|
Finite Size Effects on the QCD Spectrum Revisited
|
We have continued our study of finite size effects in the QCD spectrum on
lattices ranging in size from $8^3\times 24$ to $16^3\times24$. We have
increased our statistics for quark mass $am_q=0.025$ for the smallest lattice
size. In addition, we have studied quark mass 0.0125 for lattice sizes
$12^3\times24$ and $16^3\times24$. These lattice sizes correspond to a box
1.8--3.6 fm on a side when the rho mass at zero quark mass is used to set the
scale. We discuss the nucleon to rho mass ratio at a smaller value of
$m_\pi/m_\rho$ than previously studied with two dynamical flavors.
| 1992-11-03
| 2012-08-27
|
[
"hep-lat"
] |
The MILC Collaboration: C. Bernard, T. A. DeGrand, C. DeTar, Steven
Gottlieb, A. Krasnitz, R. Authors: L. Sugar, and D. Toussaint
|
hep-lat/9211005
|
Problems with the Quenched Approximation in the Chiral Limit
|
In the quenched approximation, loops of the light singlet meson (the $\eta'$)
give rise to a type of chiral logarithm absent in full QCD. These logarithms
are singular in the chiral limit throwing doubt upon the utility of the
quenched approximation. In previous work, I summed a class of diagrams, leading
to non-analytic power dependencies such as $\cond\propto
m_q^{-\delta/(1+\delta)}$. I suggested, however, that these peculiar results
could be redefined away. Here I give an alternative derivation of the results,
based on the renormalization group, and argue that they cannot be redefined
away. I discuss the evidence (or lack thereof) for such effects in numerical
data.
| 1992-11-02
| 2009-10-22
|
[
"hep-lat",
"hep-ph"
] |
Stephen Sharpe
|
hep-lat/9211002
|
The Running Coupling from SU(3) Potentials
|
From an accurate determination of the inter-quark potential, one can study
the running coupling constant for a range of $R$-values and hence estimate the
scale $\Lambda_{\overline{\rm MS}}$. Detailed results are presented for $SU(3)$
pure gauge theory from a study of a $36^4$ lattice at $\beta=6.5$. (to appear
in Proceedings of Lattice 1992 - Amsterdam)
| 1992-11-02
| 2019-08-17
|
[
"hep-lat"
] |
UKQCD Collaboration (presented by Chris Michael)
|
hep-lat/9211004
|
The Degrees of Freedom in Hot Quenched QCD
|
In quenched QCD, on lattices with $\nt=4$, the absence of a pole in the
pseudoscalar meson channel for $T>T_c$ is demonstrated. A set of effective
4-fermi couplings is extracted. It is observed that this coupling is small in
the vector channel for all $T>T_c$, but not in the pseudoscalar channel. The
temperature dependence of hadronic parameters below \tc{} is found to be small.
NOTE: Latex source, no figures, needs espcrc2.sty from hep-lat macros.
| 1992-11-02
| 2010-11-01
|
[
"hep-lat",
"hep-ph",
"nucl-th"
] |
Sourendu Gupta
|
hep-lat/9211001
|
Pure-gauge SU(2) on large lattices
|
We have calculated the $q\bar q$ potential over a wide range of lattice
separations on a $48^3\cdot56$ lattice at $\beta = 2.85$. We are able to
investigate both long-range and (by correcting for the effects of lack of
rotational invariance) short-range potentials. From the former we estimate the
string tension and from the latter we are able to investigate asymptotic
scaling. Fitting to this enables us to give an estimate for the
$\Lambda$-parameter of pure-gauge SU(2).
| 1992-11-02
| 2019-08-21
|
[
"hep-lat"
] |
UKQCD collaboration (presented by P.W. Stephenson)
|
hep-lat/9211003
|
Hadron Spectroscopy with Dynamical Wilson Fermions at beta=5.3
|
We present results from simulations of lattice QCD using two flavors of
dynamical Wilson fermions at a lattice coupling $\beta=5.3$ on $16^3 \times 32$
lattices at two hopping parameters, $\kappa=0.1670$ and $0.1675$, leading to
$m_\pi \approx 0.44$ and $0.33$ respectively. We show spectroscopy for S-wave
hadrons and compare our results to other recent simulations with dynamical
Wilson fermions. (Complete postscript file can be obtained by anonymous ftp
from ftp.scri.fsu.edu as file "lat92.ps" from directory "pub/heller".)
| 1992-11-02
| 2009-10-22
|
[
"hep-lat"
] |
K. M. Bitar, et.al
|
hep-lat/9210042
|
The Isgur-Wise Limit on the Lattice
|
We construct the Isgur-Wise limit of QCD in a form appropriate to lattice
gauge theory techniques. The formulation permits a calculation of heavy quark
processes even when the momentum transfers are much larger than the inverse
lattice spacing. Applications include semi-leptonic heavy quark decay and
scattering processes, including the computation of the nonperturbative part of
the Isgur-Wise universal function.
| 1992-10-31
| 2010-11-01
|
[
"hep-lat",
"hep-ph"
] |
Jeffrey E. Mandula and Michael C. Ogilvie
|
hep-lat/9210041
|
The Interface Tension in Quenched QCD at the Critical Temperature
|
We present results for the confinement-deconfinement interface tension
$\alpha_{cd}$ of quenched QCD. They were obtained by applying Binder's
histogram method to lattices of size $L^2\times L_z\times L_t$ for $L_t=2$ and
$L=8,10,12\mbox{ and }14$ with $L_z=30$ for $L=8$ and $L_z=3L$ otherwise. The
use of a multicanonical algorithm and cylindrical geometries have turned out to
be crucial for the numerical studies.
| 1992-10-30
| 2009-10-22
|
[
"hep-lat"
] |
B. Grossmann, M. L. Laursen, T. Trappenberg, U. J. Wiese
|
hep-lat/9210039
|
Perturbative Corrections for Staggered Fermion Bilinears
|
We calculate the perturbative corrections to fermion bilinears that are used
in numerical simulations when extracting weak matrix elements using staggered
fermions. This extends previous calculations of Golterman and Smit, and Daniel
and Sheard. In particular, we calculate the corrections for non-local bilinears
defined in Landau gauge with gauge links excluded. We do this for the simplest
operators, i.e. those defined on a $2^4$ hypercube, and for tree level improved
operators which live on $4^4$ hypercubes. We also consider gauge invariant
operators in which the ``tadpole'' contributions are suppressed by projecting
the sums of products of gauge links back in to the gauge group. In all cases,
we find that the variation in the size of the perturbative corrections is
smaller than those with the gauge invariant unimproved operators. This is most
strikingly true for the smeared operators. We investigate the efficacy of the
mean-field method of Lepage and Mackenzie at summing up tadpole contributions.
In a companion paper we apply these results to four-fermion operators.
| 1992-10-30
| 2014-11-17
|
[
"hep-lat"
] |
Apoorva Patel and Stephen Sharpe
|
hep-lat/9210038
|
Gauge invariant extremization
|
Recently, Duncan and Mawhinney introduced a method to find saddle points of
the action in simulations of non-abelian lattice gauge theory. The idea, called
`extremization', is to minimize $\int(\delta S/\delta A_\mu)^2$ instead of the
action $S$ itself as in conventional `cooling'. The method was implemented in
an explicitly gauge variant way, however, and gauge dependence showed up in the
results. Here we present a gauge invariant formulaton of extremization on the
lattice, applicable to any gauge group and any lattice action. The procedure is
worked out in detail for U(1) and SU(N) lattice gauge theory with the plaquette
action.
| 1992-10-29
| 2016-08-31
|
[
"hep-lat"
] |
A.J. van der Sijs
|
hep-lat/9210040
|
On reflection positive formulation of chiral gauge theories on a lattice
|
A formulation of chiral gauge theories on a lattice which is both reflection
positive and gauge invariant is discussed.
| 1992-10-28
| 2009-10-22
|
[
"hep-lat"
] |
Sergei V. Zenkin
|
hep-lat/9210036
|
Meson-Meson Scattering in Lattice QED_2+1
|
Scattering phase shifts of a meson-meson system in staggered 3-dimensional
lattice QED are computed. The main task of the simulation is to obtain a
discrete set of two-body energy levels. These are extracted from a 4-point time
correlation matrix and then used to obtain scattering phase shifts. The results
for the l=0 and l=2 partial waves are consistent with short- range repulsion
and intermediate-range attraction of the residual meson- meson interaction.
| 1992-10-28
| 2009-10-22
|
[
"hep-lat"
] |
H. R. Fiebig (Physics Department FIU University Park Miami, Florida
33199, USA) and R. M. Woloshyn (TRIUMF, 4004 Wesbrook Mall, Vancouver, B.C.,
Canada)
|
hep-lat/9210037
|
The Shape of Inflated Vesicles
|
The conformation and scaling properties of self-avoiding fluid vesicles with
zero extrinsic bending rigidity subject to an internal pressure increment
$\Delta p>0$ are studied using Monte Carlo methods and scaling arguments. With
increasing pressure, there is a first-order transition from a collapsed
branched polymer phase to an extended inflated phase. The scaling behavior of
the radius of gyration, the asphericities, and several other quantities
characterizing the average shape of a vesicle are studied in detail. In the
inflated phase, continuously variable fractal shapes are found to be controlled
by the scaling variable $x=\Delta p N^{3\nu/2}$ (or equivalently, $y = {<V>}/
N^{3\nu/2}$), where $N$ is the number of monomers in the vesicle and $V$ the
enclosed volume. The scaling behavior in the inflated phase is described by a
new exponent $\nu=0.787\pm 0.02$.
| 1992-10-28
| 2009-10-22
|
[
"hep-lat",
"cond-mat"
] |
G. Gompper and D.M. Kroll
|
hep-lat/9210035
|
A better large $N$ expansion for chiral Yukawa models
|
We consider the most general renormalizable chiral Yukawa model with
$SU(3)_{\rm color}$ replaced by $SU(N_c)$, $SU(2)_{\rm L}$ replaced by $SU(N_w
)$ and $U(1)_{Y}$ replaced by $U(1)^{N_w -1}$ in the limit $N_c
\rightarrow\infty$, $N_w \rightarrow\infty$ with the ratio
$\rho=\sqrt{{N_w}\over{N_c}} \ne 0,\infty$ held fixed. Since for $N_w \ge 3$
only one renormalizable Yukawa coupling per family exists and there is no
mixing between families the limit is appropriate for the description of the
effects of a heavy top quark when all the other fermions are taken to be
massless. The large $N=\sqrt{N_{c} N_{w}}$ expansion is expected to be no worse
quantitatively in this model that in the purely scalar case and the $N=\infty$
limit is soluble even when the model is regularized non--perturbatively. A
rough estimate of the triviality bound on the Yukawa coupling is equivalent to
$m_t \le 1~TeV$.
| 1992-10-28
| 2009-10-22
|
[
"hep-lat",
"hep-ph",
"hep-th"
] |
George Bathas and Herbert Neuberger
|
hep-lat/9210033
|
The effective potential and the renormalisation group
|
We discuss renormalisation group improvement of the effective potential both
in general and in the context of $O(N)$ scalar $\p^4$ and the Standard Model.
In the latter case we find that absolute stability of the electroweak vacuum
implies that $m_H\geq 1.95m_t-189~GeV$, for $\as (M_Z) = 0.11$. We point out
that the lower bound on $m_H$ {\it decreases\/} if $\as (M_Z)$ is increased.
| 1992-10-27
| 2009-10-22
|
[
"hep-lat",
"hep-ph"
] |
C. Ford, D.R.T. Jones, P.W. Stephenson and M.B. Einhorn
|
hep-lat/9210034
|
The $I=1$, $J=1$ channel of the O(4) $\lambda \phi^4_4$ theory
|
A Monte Carlo simulation of the $O(4)$ $\lambda \phi^4$ theory in the broken
phase is performed on a hypercubic lattice in search of an $I=1$, $J=1$
resonance. We investigate the region of the cutoff theory where the interaction
is strong as it is there that a resonance would be expected to have a better
chance to form. In that region the presence of an $I=1$, $J=1$ resonance with
mass below the cutoff is excluded. NOTE: The full ps file is also available via
anonymous ftp to ftp.scri.fsu.edu. To get the ps file, ftp to this address and
use for username "anonymous" and for password your name. The file is in the
directory pub/vranas (to go to that directory type: cd pub/vranas) and is
called lat92_proc_rho.ps (to get it type: get lat92_proc_rho.ps)
| 1992-10-27
| 2009-10-22
|
[
"hep-lat"
] |
Khalil M. Bitar, Pavlos Vranas
|
hep-lat/9210030
|
Dual Superconductor Mechanism of Confinement on the Lattice
|
We investigate the dual superconductor mechanism of confinement for pure
SU(2) lattice gauge theory in the maximally abelian gauge. We focus on the the
dual Meissner effect. We find that the transverse distribution of the
longitudinal chromoelectric field due to a static quark-antiquark pair
satisfies the dual London equation. Moreover we show that the size of the flux
tube scales according to asymptotic freedom.
| 1992-10-26
| 2008-11-26
|
[
"hep-lat"
] |
P. Cea and L. Cosmai
|
hep-lat/9210031
|
Some universal features of the effective string picture of pure gauge
theories
|
The effective string describing the large distance behaviour of the quark
sources of gauge field theories in the confining phase in D=3 or D=4 space-time
dimensions can be formulated, in the infrared limit, as a suitable 2D conformal
field theory on surfaces with quark loops as boundaries. Recent results on
self-avoiding random surfaces allow to fix almost uniquely such a conformal
theory. As a consequence, some universal relationships among the string tension
, the thickness of the colour flux tube, the deconfinement temperature and a
lower bound of the glueball mass spectrum are found. The general agreement with
the data extracted from recent lattice simulations with different gauge groups
is rather impressive.(Talk held by F.Gliozzi at Lattice'92 , Amsterdam)
| 1992-10-26
| 2009-10-22
|
[
"hep-lat",
"hep-th"
] |
M.Caselle, F.Gliozzi and S.Vinti
|
hep-lat/9210029
|
Renormalisation of lattice currents and the calculation of decay
constants for dynamical staggered fermions
|
A numerical calculation of the lattice staggered renormalisation constants at
$\beta = 5.35$, $m = 0.01$ is presented. It is seen that there are considerable
non-perturbative effects present. As an application the vector decay constant
$f_\rho$ is estimated. (LAT92 contribution, one LATEX file with 3 postscript
figures appended.)
| 1992-10-23
| 2009-10-22
|
[
"hep-lat"
] |
R. Altmeyer, K. D. Born, M. Goeckeler, R. Horsley, E. Laermann and G.
Schierholz
|
hep-lat/9210028
|
The Savvidy ``ferromagnetic vacuum'' in three-dimensional lattice gauge
theory
|
The vacuum effective potential of three-dimensional SU(2) lattice gauge
theory in an applied color-magnetic field is computed over a wide range of
field strengths. The background field is induced by an external current, as in
continuum field theory. Scaling and finite volume effects are analyzed
systematically. The first evidence from lattice simulations is obtained of the
existence of a nontrivial minimum in the effective potential. This supports a
``ferromagnetic'' picture of gluon condensation, proposed by Savvidy on the
basis of a one-loop calculation in (3+1)-dimensional QCD.
| 1992-10-23
| 2009-10-22
|
[
"hep-lat",
"hep-th"
] |
Howard D. Trottier and R. M. Woloshyn
|
hep-lat/9210032
|
Regularity Properties and Pathologies of Position-Space
Renormalization-Group Transformations
|
We reconsider the conceptual foundations of the renormalization-group (RG)
formalism, and prove some rigorous theorems on the regularity properties and
possible pathologies of the RG map. Regarding regularity, we show that the RG
map, defined on a suitable space of interactions (= formal Hamiltonians), is
always single-valued and Lipschitz continuous on its domain of definition. This
rules out a recently proposed scenario for the RG description of first-order
phase transitions. On the pathological side, we make rigorous some arguments of
Griffiths, Pearce and Israel, and prove in several cases that the renormalized
measure is not a Gibbs measure for any reasonable interaction. This means that
the RG map is ill-defined, and that the conventional RG description of
first-order phase transitions is not universally valid. For decimation or
Kadanoff transformations applied to the Ising model in dimension $d \ge 3$,
these pathologies occur in a full neighborhood $\{ \beta > \beta_0 ,\, |h| <
\epsilon(\beta) \}$ of the low-temperature part of the first-order
phase-transition surface. For block-averaging transformations applied to the
Ising model in dimension $d \ge 2$, the pathologies occur at low temperatures
for arbitrary magnetic-field strength. Pathologies may also occur in the
critical region for Ising models in dimension $d \ge 4$. We discuss in detail
the distinction between Gibbsian and non-Gibbsian measures, and give a rather
complete catalogue of the known examples. Finally, we discuss the heuristic and
numerical evidence on RG pathologies in the light of our rigorous theorems.
| 1992-10-22
| 2015-06-25
|
[
"hep-lat"
] |
A.C.D. van Enter, R. Fernandez and A.D. Sokal
|
hep-lat/9210026
|
Regularization dependence of the Higgs mass triviality bound
|
We calculate the triviality bound on the Higgs mass in scalar field theory
models whose global symmetry group $SU(2)_L \times SU(2)_{\rm custodial}
\approx O(4)$ has been replaced by $O(N)$ and $N$ has been taken to infinity.
Limits on observable cutoff effects at four percent in several regularized
models with tunable couplings in the bare action yield triviality bounds
displaying a large degree of universality. Extrapolating from $N=\infty$ to
$N=4$ we conservatively estimate that a Higgs particle with mass up to
$0.750~TeV$ and width up to $0.290~TeV$ is realizable without large cutoff
effects, indicating that strong scalar self interactions in the standard model
are not ruled out. We also present preliminary numerical results of the
physical $N=4$ case for the $F_4$ lattice that are in agreement with the large
$N$ expectations. Note: The full ps file is also available via anonymous ftp to
ftp.scri.fsu.edu. To get the ps file, ftp to this address and use for username
"anonymous" and for password your name. The file is in the directory pub/vranas
(to go to that directory type: cd pub/vranas) and is called lat92_proc.ps (to
get it type: get lat92_proc.ps)
| 1992-10-22
| 2009-10-22
|
[
"hep-lat"
] |
Urs M. Heller, Markus Klomfass, Herbert Neuberger and Pavlos Vranas
|
hep-lat/9210027
|
Nonperturbative evaluation of the diffusion rate in field theory at high
temperatures
|
Kramer's approach to the rate of the thermally activated escape from a
metastable state is extended to field theory. Diffusion rate in the
1+1-dimensional Sine-Gordon model as a function of temperature and friction
coefficient is evaluated numerically by solving the Langevin equation in real
time. A clear crossover from the semiclassical to the high temperature domain
is observed. The temperature behaviour of the diffusion rate allows one to
determine the kink mass which is found equal to the corresponding classical
value. The Kramer's predictions for the dependence on viscosity are
qualitatively valid in this multidimensional case. In the limit of vanishing
friction the diffusion rate is shown to coincide with the one obtained from the
direct measurements of the conventional classical real-time Green function at
finite temperature.
| 1992-10-22
| 2009-10-22
|
[
"hep-lat"
] |
Alexander Bochkarev and Philippe de Forcrand
|
hep-lat/9210025
|
Theoretical Analysis of Acceptance Rates in Multigrid Monte Carlo
|
We analyze the kinematics of multigrid Monte Carlo algorithms by
investigating acceptance rates for nonlocal Metropolis updates. With the help
of a simple criterion we can decide whether or not a multigrid algorithm will
have a chance to overcome critial slowing down for a given model. Our method is
introduced in the context of spin models. A multigrid Monte Carlo procedure for
nonabelian lattice gauge theory is described, and its kinematics is analyzed in
detail.
| 1992-10-22
| 2009-10-22
|
[
"hep-lat"
] |
Martin Grabenstein and Klaus Pinn
|
hep-lat/9210023
|
Scattering in a Simple 2-d Lattice Model
|
L\"uscher has suggested a method to determine phase shifts from the finite
volume dependence of the two-particle energy spectrum. We apply this to two
models in d=2: (a) the Ising model, (b) a system of two Ising fields with
different mass and coupled through a 3-point term, both considered in the
symmetric phase. The Monte Carlo simulation makes use of the cluster updating
and reduced variance operator techniques. For the Ising system we study in
particular O($a^2$) effects in the phase shift of the 2-particle scattering
process.
| 1992-10-21
| 2009-10-22
|
[
"hep-lat"
] |
C.R. Gattringer, I. Hip and C.B. Lang
|
hep-lat/9210024
|
Dual of 3-dimensional pure SU(2) Lattice Gauge Theory and the
Ponzano-Regge Model
|
By carrying out character expansion and integration over all link variables,
the partition function of 3-dimensional pure SU(2) lattice gauge theory is
rewritten in terms of 6j symbols. The result is Ponzano-Regge model of
3-dimensional gravity with a term that explicitly breaks general coordinate
invariance. Conversely, we show that dual of Ponzano-Regge model is an SU(2)
lattice gauge theory where all plaquette variables are constrained to the
identity matrix and therefore the model needs no further regularization. Our
techniques are applicable to other models with non-abelian symmetries in any
dimension and provide duality transform for the partition function.
| 1992-10-21
| 2009-10-22
|
[
"hep-lat",
"cond-mat"
] |
Ramesh Anishetty, Srinath Cheluvaraja, H.S. Sharatchandra and Manu
Mathur
|
hep-lat/9210021
|
The String Tension in Gauge Theories: a Suggestion for a New Measurement
Method
|
We discuss a new method for testing confinement and measuring the string
tension (in the Coulomb gauge). Our numerical simulations demonstrate that the
problems related to Gribov copies are not harmful and that the method is
effective in the case of pure gauge Q.C.D.. We discuss the relevance of the
method for studying gauge theories coupled to fermionic matter.
| 1992-10-19
| 2009-10-22
|
[
"hep-lat"
] |
E. Marinari, M. L. Paciello, G. Parisi and B. Taglienti
|
hep-lat/9210022
|
Fermion-Higgs model with strong Wilson-Yukawa coupling in two dimensions
|
The fermion mass spectrum is studied in the quenched approximation in the
strong coupling vortex phase (VXS) of a globally U(1)$_L \otimes$U(1)$_R$
symmetric scalar-fermion model in two dimensions. In this phase fermion
doublers can be completely removed from the physical spectrum by means of a
strong Wilson-Yukawa coupling. The lowest lying fermion spectrum in this phase
consists most probably only of a massive Dirac fermion which has charge zero
with respect to the $U(1)_L$ group. We give evidence that the fermion which is
charged with respect to that subgroup is absent in the VXS phase. When the
$U(1)_L$ gauge fields are turned on, the neutral fermion may couple chirally to
the massive vector boson state in the confinement phase. The outcome is very
similar to our findings in the strong coupling symmetric phase (PMS) of
fermion-Higgs models with Wilson-Yukawa coupling in four dimensions, with the
exception that in four dimensions the neutral fermion does most probably
decouple from the bosonic bound states.
| 1992-10-19
| 2009-10-22
|
[
"hep-lat"
] |
Wolfgang Bock, Asit K. De, Erich Focht and Jan Smit
|
hep-lat/9210020
|
Intermittency Studies in Directed Bond Percolation
|
The self-similar cluster fluctuations of directed bond percolation at the
percolation threshold are studied using techniques borrowed from
inter\-mit\-ten\-cy-related analysis in multi-particle production. Numerical
simulations based on the factorial moments for large $1+1$-dimensional lattices
allow to handle statistical and boundary effects and show the existence of weak
but definite intermittency patterns. The extracted fractal dimensions are in
agreement with scaling arguments leading to a new relation linking the
intermittency indices to the critical exponents and the fractal dimension of
directed percolation clusters.
| 1992-10-16
| 2008-11-26
|
[
"hep-lat",
"cond-mat",
"hep-th"
] |
Malte Henkel and Robert Peschanski
|
hep-lat/9210019
|
Bosonization and Cluster Updating of Lattice Fermions
|
A lattice fermion model is formulated in Fock space using the Jordan-Wigner
representation for the fermion creation and annihilation operators. The
resulting path integral is a sum over configurations of lattice site occupation
numbers $n(x,t) = 0,1$ which may be viewed as bosonic Ising-like variables.
However, as a remnant of Fermi statistics a nonlocal sign factor arises for
each configuration. When this factor is included in measured observables the
bosonic occupation numbers interact locally, and one can use efficient cluster
algorithms to update the bosonized variables.
| 1992-10-16
| 2009-10-22
|
[
"hep-lat",
"cond-mat"
] |
Uwe-Jens Wiese (Universit\"at Bern)
|
hep-lat/9210017
|
Lee-Yang Zeroes and Logarithmic Corrections in the $\Phi^4_4$ Theory
|
The leading mean-field critical behaviour of $\phi^4_4$-theory is modified by
multiplicative logarithmic corrections. We analyse these corrections both
analytically and numerically. In particular we present a finite-size scaling
theory for the Lee-Yang zeroes and temperature zeroes, both of which exhibit
logarithmic corrections. On lattices from size $8^4$ to $24^4$, Monte-Carlo
cluster methods and multi-histogram techniques are used to determine the
partition function zeroes closest to the critical point. Finite-size scaling
behaviour is verified and the logarithmic corrections are found to be in good
agreement with our analytical predictions.
| 1992-10-13
| 2009-10-22
|
[
"hep-lat"
] |
R. Kenna and C.B. Lang
|
hep-lat/9210018
|
The Kaon $B$-parameter with Wilson Fermions
|
We calculate the kaon $B$-parameter in quenched lattice QCD at $\beta=6.0$
using Wilson fermions at $\kappa=0.154$ and $0.155$. We use two kinds of
non-local (``smeared'') sources for quark propagators to calculate the matrix
elements between states of definite momentum. The use of smeared sources yields
results with much smaller errors than obtained in previous calculations with
Wilson fermions. By combining results for $\vec p =(0,0,0)$ and $\vec p
=(0,0,1)$, we show that one can carry out the non-perturbative subtraction
necessary to remove the dominant lattice artifacts induced by the chiral
symmetry breaking term in the Wilson action. Our final results are in good
agreement with those obtained using staggered fermions. We also present results
for $B$-parameters of the $\Delta I = 3/2$ part of the electromagnetic penguin
operators, and preliminary results for \bk\ in the presence of two flavors of
dynamical quarks.
| 1992-10-13
| 2009-10-22
|
[
"hep-lat"
] |
Gupta, Daniel, Kilcup, Patel and Sharpe
|
hep-lat/9210016
|
Improvement of efficiency in generating random $U(1)$ variables with
Boltzmann distribution
|
A method for generating random $U(1)$ variables with Boltzmann distribution
is presented. It is based on the rejection method with transformation of
variables. High efficiency is achieved for all range of temparatures or
coupling parameters, which makes the present method especially suitable for
parallel and pipeline vector processing machines. Results of computer runs are
presented to illustrate the efficiency. An idea to find such algorithms is also
presented, which may be applicable to other distributions of interest in Monte
Carlo simulations.
| 1992-10-10
| 2009-10-22
|
[
"hep-lat"
] |
Tetsuya Hattori and Hideo Nakajima
|
hep-lat/9210014
|
The U(1)-Higgs Model: Critical Behaviour in the Confinig-Higgs region
|
We study numerically the critical properties of the U(1)-Higgs lattice model,
with fixed Higgs modulus, in the region of small gauge coupling where the Higgs
and Confining phases merge. We find evidence of a first order transition line
that ends in a second order point. By means of a rotation in parameter space we
introduce thermodynamic magnitudes and critical exponents in close resemblance
with simple models that show analogous critical behaviour. The measured data
allow us to fit the critical exponents finding values in agreement with the
mean field prediction. The location of the critical point and the slope of the
first order line are accurately given.
| 1992-10-09
| 2008-11-26
|
[
"hep-lat"
] |
Alonso, Azcoiti, Campos, Ciria, Cruz, Iniguez, lesmes, Piedrafita,
Rivero, Tarancon, Badoni, Fernandez, Munoz Sudupe, Ruiz Lorenzo, Gonzalez
Arroyo, Martinez, Pech and Tellez
|
hep-lat/9210015
|
The nature of the continuum limit in strongly coupled quenched QED
|
We review the results of large scale simulations of noncompact quenched $QED$
which use spectrum and Equation of State calculations to determine the theory's
phase diagram, critical indices, and continuum limit. The resulting anomalous
dimensions are in good agreement with Schwinger-Dyson solutions of the ladder
graphs of conventional $QED$ and they satisfy the hyperscaling relations
expected of a relativistic renormalizable field theory. The spectroscopy
results satisfy the constraints of the Goldstone mechanism and PCAC, and may be
indicative of Technicolor versions of the Standard Model which are strongly
coupled at short distances.
| 1992-10-09
| 2009-10-22
|
[
"hep-lat",
"hep-ph"
] |
Mp Lombardo, J.B. Kogut, A. Kocic and K.C. Wang
|
hep-lat/9210011
|
$1/N$ Expansion of Two-Dimensional Models in the Scaling Region
|
The main technical and conceptual features of the lattice $1/N$ expansion in
the scaling region are discussed in the context of a two-parameter
two-dimensional spin model interpolating between $CP^{N-1}$ and $O(2N)$
$\sigma$ models, with standard and improved lattice actions. We show how to
perform the asymptotic expansion of effective propagators for small values of
the mass gap and how to employ this result in the evaluation of physical
quantities in the scaling regime. The lattice renormalization group $\beta$
function is constructed explicitly and exactly to $O({1/N})$.
| 1992-10-08
| 2009-10-22
|
[
"hep-lat"
] |
Massimo Campostrini and Paolo Rossi
|
hep-lat/9210010
|
Scaling and asymptotic scaling in two-dimensional $CP^{N-1}$ models
|
Two-dimensional $CP^{N-1}$ models are investigated by Monte Carlo methods on
the lattice, for values of $N$ ranging from 2 to 21. Scaling and rotation
invariance are studied by comparing different definitions of correlation length
$\xi$. Several lattice formulations are compared and shown to enjoy scaling for
$\xi$ as small as $2.5$. Asymptotic scaling is investigated using as bare
coupling constant both the usual $\beta$ and $\beta_E$ (related to the internal
energy); the latter is shown to improve asymptotic scaling properties. Studies
of finite size effects show their $N$-dependence to be highly non-trivial, due
to the increasing radius of the $\bar z z$ bound states at large $N$.
| 1992-10-08
| 2009-10-22
|
[
"hep-lat"
] |
Massimo Campostrini, Paolo Rossi, and Ettore Vicari
|
hep-lat/9210012
|
Topological susceptibility and string tension in CP(N-1) models
|
We investigate the features of ${\rm CP}^{N-1}$ models concerning confinement
and topology. In order to study the approach to the large-$N$ asymptotic
regime, we determine the topological susceptibility and the string tension for
a wide range of values of $N$, in particular $N=4,10,21,41$. Quantitative
agreement with the large-$N$ predictions is found for the ${\rm CP}^{20}$ and
the ${\rm CP}^{40}$ models. Problems related to the measure of the topological
susceptibility and the string tension on the lattice are discussed.
| 1992-10-08
| 2009-10-22
|
[
"hep-lat"
] |
Massimo Campostrini, Paolo Rossi, and Ettore Vicari (Dipartimento di
Fisica dell'Universit\`a and Istituto Nazionale di Fisica Nucleare, I-56126
Pisa, Italy)
|
hep-lat/9210013
|
Wave functions and their use in spectroscopy and phenomenology
|
We describe the calculation of Coulomb gauge wave functions for light quark
systems, and their use as interpolating fields for excited state spectroscopy.
| 1992-10-08
| 2009-10-22
|
[
"hep-lat"
] |
T. DeGrand and M. Hecht
|
hep-lat/9210009
|
Renormalization Group Analysis of Finite-Size Scaling in the $\Phi^4_4$
Model
|
A finite-size scaling theory for the $\phi^4_4$ model is derived using
renormalization group methods. Particular attention is paid to the partition
function zeroes, in terms of which all thermodynamic observables can be
expressed. While the leading scaling behaviour is identical to that of mean
field theory, there exist multiplicative logarithmic corrections too. A
non-perturbative test of these formulae in the form of a high precision Monte
Carlo analysis reveals good quantitative agreement with the analytical
predictions.
| 1992-10-07
| 2009-10-22
|
[
"hep-lat"
] |
R. Kenna and C.B. Lang
|
hep-lat/9210008
|
SU(N) Gauge Theories with C-Periodic Boundary Conditions: II. Small
Volume Dynamics
|
The dynamics of SU(N) gauge theories, especially for N=3, in a small
C-periodic box are investigated. We identify the fields that mimimize the
energy---the torons---and determine which of these ``classical'' vacua are
stable quantum mechanically. The stable torons break cubic symmetry, which has
interesting consequences on the spectrum. At any of the stable torons there are
also quartic modes. Since all C-periodic boundary conditions are
gauge-equivalent, we choose a convenient version, for which the quartic modes
are constant modes, and compute the effective Hamiltonian to one loop in
perturbation theory.
| 1992-10-07
| 2009-10-22
|
[
"hep-lat",
"hep-th"
] |
A.S. Kronfeld and U.-J. Wiese
|
hep-lat/9210007
|
The infrared limit of QCD effective string
|
Some model-independent properties of the effective string of gauge field
systems in the confining phase , for very large quark separations, are
described in terms of two-dimensional conformal field theories. The constraints
induced by the gauge theory at the boundaries of the effective string induce a
Coulomb- like term in the interquark potential which is universal, but
different from the one proposed by L\"uscher. Some universal relations among
the string tension, the thickness of the colour flux tube, the location of the
deconfining temperature and a lower bound of the glueball spectrum are
discussed. (Lectures given at the XXXII Cracow School of Theoretical Physics,
Zakopane, Poland 2-12 June 1992)
| 1992-10-06
| 2011-04-15
|
[
"hep-lat"
] |
F.Gliozzi
|
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