307 research outputs found
A remark on the BRST symmetry in the Gribov-Zwanziger theory
We show that the soft breaking of the BRST symmetry arising in the
Gribov-Zwanziger theory can be converted into a linear breaking upon
introduction of a set of BRST quartets of auxiliary fields. Due to its
compatibility with the Quantum Action Principle, the linearly broken BRST
symmetry can be directly converted into a suitable set of useful Slavnov-Taylor
identities. As a consequence, it turns out that the renormalization aspects of
the Gribov-Zwanziger theory can be addressed by means of the cohomology of a
nilpotent local operatorComment: 11 pages, final version to appear in Phys. Rev.
Study of the Gribov region in Euclidean Yang-Mills theories in the maximal Abelian gauge
The properties of the Gribov region in SU(2) Euclidean Yang-Mills theories in
the maximal Abelian gauge are investigated. This region turns out to be bounded
in all off-diagonal directions, while it is unbounded along the diagonal one.
The soft breaking of the BRST invariance due to the restriction of the domain
of integration in the path integral to the Gribov region is scrutinized. Owing
to the unboundedness in the diagonal direction, the invariance with respect to
Abelian transformations is preserved, a property which is at the origin of the
local U(1) Ward identity of the maximal Abelian gauge.Comment: 15 pages, one reference added, version accepted for publication in
Phys. Rev.
Renormalizability of the linearly broken formulation of the BRST symmetry in presence of the Gribov horizon in Landau gauge Euclidean Yang-Mills theories
In previous work arXiv:1009.4135 we have shown that the soft breaking of the
BRST symmetry arising within the Gribov-Zwanziger framework can be converted
into a linear breaking, while preserving the nilpotency of the BRST operator.
Due to its compatibility with the Quantum Action Principle, the linearly broken
BRST symmetry directly translates into a set of Slavnov-Taylor identities. We
show that these identities guarantee the multiplicative renormalizability of
both Gribov-Zwanziger and Refined Gribov-Zwanziger theories to all orders. The
known property that only two renormalization factors are needed is recovered.
The non-renormalization theorem of the gluon-ghost-antighost vertex as well as
the renormalization factor of the Gribov parameter are derived within the
linearly broken formulation.Comment: 20 pages, references added, version accepted for publication in
Physical Review
The infrared behavior of the gluon and ghost propagators in SU(2) Yang-Mills theory in the maximal Abelian gauge
We report on some recent analytical results on the behaviour of the gluon and
ghost propagators in Euclidean SU(2) Yang-Mills theory quantized in the maximal
Abelian gauge (MAG). This gauge is of particular interest for the dual
superconductivity picture to explain color confinement. Two kinds of effects
are taken into account: those arising from a treatment of Gribov copies in the
MAG and those arising from a dynamical mass originating in a dimension two
gluon condensate. The diagonal component of the gluon propagator displays the
typical Gribov-type behaviour, while the off-diagonal component is of the
Yukawa type due to the dynamical mass. These results are in qualitative
agreement with available lattice data on the gluon propagators. The
off-diagonal ghost propagator exhibits an infrared enhancement due to the
Gribov restriction, while the diagonal one remains unaffected.Comment: 6 pages. Talk given by S.P. Sorella at the "I Latin American Workshop
on High Energy Phenomenology (I LAWHEP)", December 1-3 2005, Instituto de
Fisica, UFRGS, Porto Alegre, Rio Grande Do Sul, Brasi
A new picture on (3+1)D topological mass mechanism
We present a class of mappings between the fields of the Cremmer-Sherk and
pure BF models in 4D. These mappings are established by two distinct
procedures. First a mapping of their actions is produced iteratively resulting
in an expansion of the fields of one model in terms of progressively higher
derivatives of the other model fields. Secondly an exact mapping is introduced
by mapping their quantum correlation functions. The equivalence of both
procedures is shown by resorting to the invariance under field scale
transformations of the topological action. Related equivalences in 5D and 3D
are discussed. A cohomological argument is presented to provide consistency of
the iterative mapping.Comment: 13 page
A study of the gauge invariant, nonlocal mass operator in Yang-Mills theories
The nonlocal mass operator is
considered in Yang-Mills theories in Euclidean space-time. It is shown that the
operator can be cast in local
form through the introduction of a set of additional fields. A local and
polynomial action is thus identified. Its multiplicative renormalizability is
proven by means of the algebraic renormalization in the class of linear
covariant gauges. The anomalous dimensions of the fields and of the mass
operator are computed at one loop order. A few remarks on the possible role of
this operator for the issue of the gauge invariance of the dimension two
condensates are outlined.Comment: 34 page
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