80 research outputs found
Gribov copies, avalanches and dynamic generation of a gluon mass
Analytic calculations in the infrared regime of nonabelian gauge theories are
hampered by the presence of Gribov copies which results in some ambiguity in
the gauge-fixing procedure. This problem shares strong similarities with the
issue of finding the true ground state among a large number of metastable
states, a typical situation in the field of statistical physics of disordered
systems. Building on this analogy, we propose a new gauge-fixing procedure
which, we argue, makes more explicit the influence of the Gribov copies. A
1-loop calculation shows that the dynamics of these copies can lead to the
spontaneous generation of a gauge-dependent gluon mass.Comment: 5 pages, 1 figur
Scale invariance implies conformal invariance for the three-dimensional Ising model
Using Wilson renormalization group, we show that if no integrated vector
operator of scaling dimension exists, then scale invariance implies
conformal invariance. By using the Lebowitz inequalities, we prove that this
necessary condition is fulfilled in all dimensions for the Ising universality
class. This shows, in particular, that scale invariance implies conformal
invariance for the three-dimensional Ising model.Comment: Phys. Rev. E 93, 012144 (2016
Influence of Gribov ambiguities in a class of nonlinear covariant gauges
We consider Yang-Mills theories in a recently proposed family of nonlinear
covariant gauges that consistently deals with the issue of Gribov ambiguities.
Such gauges provide a generalization of the Curci-Ferrari-Delbourgo-Jarvis
gauges which can be formulated as an extremization procedure and might be
implemented in numerical calculations. This would allow for nonperturbative
studies of Yang-Mills correlators in a broad class of covariant gauges
continuously connected to the well-studied Landau gauge. We compute the ghost
and gluon propagators in the continuum formulation at one-loop order in
perturbation theory and we study their momentum dependence down to the deep
infrared regime, with and without renormalization group improvement. In
particular, we show that the theory admits infrared-safe renormalization-group
trajectories with no Landau pole. Both the gluon and the ghost behave as
massive fields at low energy, and the gluon propagator is transverse even away
from the Landau gauge limit. We compare our results to those obtained in the
usual Curci-Ferrari model, which allows us to pinpoint the specific effects
arising from our treatment of Gribov copies.Comment: 23 pages. 24 figures. One suplemental material: Mathematica file with
the full expressions of the one-loop Feynman diagram
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