2,379 research outputs found
Linear Covariant Gauges on the Lattice
Linear covariant gauges, such as Feynman gauge, are very useful in
perturbative calculations. Their nonperturbative formulation is, however,
highly non-trivial. In particular, it is a challenge to define linear covariant
gauges on a lattice. We consider a class of gauges in lattice gauge theory that
coincides with the perturbative definition of linear covariant gauges in the
formal continuum limit. The corresponding gauge-fixing procedure is described
and analyzed in detail, with an application to the pure SU(2) case. In
addition, results for the gluon propagator in the two-dimensional case are
given.Comment: 21 pages, 6 figures, 5 tables; added comments and minor changes, 1
figure added, 1 modifie
More on the non-perturbative Gribov-Zwanziger quantization of linear covariant gauges
In this paper, we discuss the gluon propagator in the linear covariant gauges
in Euclidean dimensions. Non-perturbative effects are taken into
account via the so-called Refined Gribov-Zwanziger framework. We point out
that, as in the Landau and maximal Abelian gauges, for , the gluon
propagator displays a massive (decoupling) behaviour, while for , a
scaling one emerges. All results are discussed in a setup that respects the
Becchi-Rouet-Stora-Tyutin (BRST) symmetry, through a recently introduced
non-perturbative BRST transformation. We also propose a minimizing functional
that could be used to construct a lattice version of our non-perturbative
definition of the linear covariant gauge.Comment: 15 pages, 1 figure; V2 typos fixed and inclusion of section on the
ghost propagator. To appear in PhysRev
Extended Double Lattice BRST, Curci-Ferrari Mass and the Neuberger Problem
We present Extended Double BRST on the lattice and extend the Neuberger
problem to include the ghost/anti-ghost symmetric formulation of the non-linear
covariant Curci-Ferrari (CF) gauges. We then show how a CF mass regulates the
0/0 indeterminate form of physical observables, as observed by Neuberger, and
discuss the gauge-parameter and mass dependence of the model.Comment: Prepared for 7th Conference on Quark Confinement and the Hadron
Spectrum, Ponta Delgada, Azores, Portugal, 2-7 Sep 2006. 3p
Non-perturbative treatment of the linear covariant gauges by taking into account the Gribov copies
In this paper, a proposal for the restriction of the Euclidean functional
integral to a region free of infinitesimal Gribov copies in linear covariant
gauges is discussed. An effective action, akin to the Gribov-Zwanziger action
of the Landau gauge, is obtained which implements the aforementioned
restriction. Although originally non-local, this action can be cast in local
form by introducing auxiliary fields. As in the case of the Landau gauge,
dimension two condensates are generated at the quantum level, giving rise to a
refinement of the action which is employed to obtain the tree-level gluon
propagator in linear covariant gauges. A comparison of our results with those
available from numerical lattice simulations is also provided.Comment: 21 pages, no figures, version to appear in EPJ
A study of the Gribov copies in linear covariant gauges in Euclidean Yang-Mills theories
The Gribov copies and their consequences on the infrared behavior of the
gluon propagator are investigated in Euclidean Yang-Mills theories quantized in
linear covariant gauges. Considering small values of the gauge parameter, it
turns out that the transverse component of the gluon propagator is suppressed,
while its longitudinal part is left unchanged. A Green function, G_{tr}, which
displays infrared enhancement and which reduces to the ghost propagator in the
Landau gauge is identified. The inclusion of the dimension two gluon condensate
is also considered. In this case, the transverse component of the gluon
propagator and the Green function G_{tr} remain suppressed and enhanced,
respectively. Moreover, the longitudinal part of the gluon propagator becomes
suppressed. A comparison with the results obtained from the studies of the
Schwinger-Dyson equations and from lattice simulations is provided.Comment: 20 page
A non-perturbative study of matter field propagators in Euclidean Yang-Mills theory in linear covariant, Curci-Ferrari and maximal Abelian gauges
In this work, we study the propagators of matter fields within the framework
of the Refined Gribov-Zwanziger theory, which takes into account the effects of
the Gribov copies in the gauge-fixing quantization procedure of Yang-Mills
theory. In full analogy with the pure gluon sector of the Refined
Gribov-Zwanziger action, a non-local long-range term in the inverse of the
Faddeev-Popov operator is added in the matter sector. Making use of the recent
BRST invariant formulation of the Gribov-Zwanziger framework achieved in [Capri
et al 2016], the propagators of scalar and quark fields in the adjoint and
fundamental representations of the gauge group are worked out explicitly in the
linear covariant, Curci-Ferrari and maximal Abelian gauges. Whenever lattice
data are available, our results exhibit good qualitative agreement.Comment: 27 pages, no figures; V2, minor modifications, to appear in EPJ
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