357 research outputs found
Topology and Staggered Fermion Action Improvement
It is conventional wisdom that staggered fermions do not feel gauge field
topology. However, the response of staggered fermion eigenmodes to the topology
of the gauge field can depend quite sensitively on the way in which the
staggered fermion action is improved. We study this issue using a variety of
improved staggered quark actions. We observe that the separation between the
``would be'' zero modes and the non-chiral modes increases with the level of
improvement. This enables the ``zero modes'' to be identified unambiguously.
The distribution of the remaining non-chiral modes is compared with the
predictions of Random Matrix Theory. Satisfactory agreement is obtained.Comment: Lattice 2004 (topology
The Laplacian Gauge Gluon Propagator in SU(N_c)
We examine the gluon propagator in the Laplacian gauge in quenched lattice
QCD as a function of the number of colours. We observe a weak dependence on
over the whole momentum range. This implies an almost -independent
gluon pole mass in units of the string tension.Comment: 5 pages, 7 figures. A study of the gluon propagator in SU(4) for
various lattice sizes was added. Extended version to appear in Phys. Rev.
High-Precision c and b Masses, and QCD Coupling from Current-Current Correlators in Lattice and Continuum QCD
We extend our earlier lattice-QCD analysis of heavy-quark correlators to
smaller lattice spacings and larger masses to obtain new values for the c mass
and QCD coupling, and, for the first time, values for the b mass:
m_c(3GeV,n_f=4)=0.986(6)GeV, alpha_msb(M_Z,n_f=5)=0.1183(7), and
m_b(10GeV,n_f=5)=3.617(25)GeV. These are among the most accurate determinations
by any method. We check our results using a nonperturbative determination of
the mass ratio m_b(mu,n_f)/m_c(mu,n_f); the two methods agree to within our 1%
errors and taken together imply m_b/m_c=4.51(4). We also update our previous
analysis of alpha_msb from Wilson loops to account for revised values for r_1
and r_1/a, finding a new value alpha_\msb(M_Z,n_f=5)=0.1184(6); and we update
our recent values for light-quark masses from the ratio m_c/m_s. Finally, in
the Appendix, we derive a procedure for simplifying and accelerating
complicated least-squares fits.Comment: 16 pages, 10 figures, 3 table
A Geometric Monte Carlo Algorithm for the Antiferromagnetic Ising model with "Topological" Term at
In this work we study the two and three-dimensional antiferromagnetic Ising
model with an imaginary magnetic field at . In order to
perform numerical simulations of the system we introduce a new geometric
algorithm not affected by the sign problem. Our results for the model are
in agreement with the analytical solutions. We also present new results for the
model which are qualitatively in agreement with mean-field predictions
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