298 research outputs found
Pad\'e approximation and glueball mass estimates in 3d and 4d with N_c = 2,3 colors
A Pad\'e approximation approach, rooted in an infrared moment technique, is
employed to provide mass estimates for various glueball states in pure gauge
theories. The main input in this analysis are theoretically well-motivated fits
to lattice gluon propagator data, which are by now available for both SU(2) and
SU(3) in 3 and 4 space-time dimensions. We construct appropriate gauge
invariant and Lorentz covariant operators in the (pseudo)scalar and
(pseudo)tensor sector. Our estimates compare reasonably well with a variety of
lattice sources directly aimed at extracting glueball masses.Comment: 11 pages, 5 .png figures. v2: extra figure, calculational details and
references; improved presentation and title. Version to appear in Phys.Lett.
More on the renormalization of the horizon function of the Gribov-Zwanziger action and the Kugo-Ojima Green function(s)
In this paper we provide strong evidence that there is no ambiguity in the
choice of the horizon function underlying the Gribov-Zwanziger action. We show
that there is only one correct possibility which is determined by the
requirement of multiplicative renormalizability. As a consequence, this means
that relations derived from other horizon functions cannot be given a
consistent interpretation in terms of a local and renormalizable quantum field
theory. In addition, we also discuss that the Kugo-Ojima functions and
can only be defined after renormalization of the underlying Green
function(s).Comment: 16 pages, some typo's correcte
Ghost Condensates and Dynamical Breaking of SL(2,R) in Yang-Mills in the Maximal Abelian Gauge
Ghost condensates of dimension two in SU(N) Yang-Mills theory quantized in
the Maximal Abelian Gauge are discussed. These condensates turn out to be
related to the dynamical breaking of the SL(2,R) symmetry present in this gaugeComment: 16 pages, LaTeX2e, final version to appear in J. Phys.
From propagators to glueballs in the Gribov-Zwanziger framework
Over the last years, lattice calculations in pure Yang-Mills gauge theory
seem to have come more or less to a consensus. The ghost propagator is not
enhanced and the gluon propagator is positivity violating, infrared suppressed
and non-vanishing at zero momentum. From an analytical point of view, several
groups are agreeing with these results. Among them, the refined
Gribov-Zwanziger (RGZ) framework also accommodates for these results. The
question which rises next is, if our models hold the right form for the
propagators, how to extract information on the real physical observables, i.e.
the glueballs? How do the operators which represent glueballs look like? We
review the current status of this matter within the RGZ framework.Comment: 3 pages, Conference contribution for Confinement IX, Madrid 2010
(30/08-03/09), to appear in American Institute of Physics (AIP
The effects of Gribov copies in 2D gauge theories
In previous works, we have shown that the Gribov-Zwanziger action, which
implements the restriction of the domain of integration in the path integral to
the Gribov region, generates extra dynamical effects which influence the
infrared behaviour of the gluon and ghost propagator in SU(N) Yang-Mills gauge
theories. The latter are in good agreement with the most recent lattice data
obtained at large volumes, both in 4D and in 3D. More precisely, the gluon
propagator is suppressed and does not vanish at zero momentum, while the ghost
propagator keeps a 1/p^2 behaviour for p^2\approx0. Instead, in 2D, the lattice
data revealed a vanishing zero momentum gluon propagator and an infrared
enhanced ghost, in support of the usual Gribov-Zwanziger scenario. We will now
show that the 2D version of the Gribov-Zwanziger action still gives results in
qualitative agreement with these lattice data, as the peculiar infrared nature
of 2D gauge theories precludes the analogue of the dynamical effect otherwise
present in 4D and 3D. Simultaneously, we also observe that the Gribov-Zwanziger
restriction serves as an infrared regulating mechanism.Comment: 10 pages, 1 .eps figur
Accessing the topological susceptibility via the Gribov horizon
The topological susceptibility, , following the work of Witten and
Veneziano, plays a key role in identifying the relative magnitude of the
mass, the so-called problem. A nonzero is
caused by the Veneziano ghost, the occurrence of an unphysical massless pole in
the correlation function of the topological current. In a recent paper
(Phys.Rev.Lett.114 (2015) 24, 242001), an explicit relationship between this
Veneziano ghost and color confinement was proposed, by connecting the dynamics
of the Veneziano ghost, and thus the topological susceptibility, with Gribov
copies. However, the analysis is incompatible with BRST symmetry (Phys.Rev.D 93
(2016) no.8, 085010). In this paper, we investigate the topological
susceptibility, , in SU(3) and SU(2) Euclidean Yang-Mills theory using
an appropriate Pad\'e approximation tool and a non-perturbative gluon
propagator, within a BRST invariant framework and by taking into account Gribov
copies in a general linear covariant gauge.Comment: 17 pages, 4 figures. v2: corrected typos, new figures, improved style
of presentatio
Remarks on the Gribov horizon and dynamical mass generation in Euclidean Yang-Mills theories
The effect of the dynamical mass generation on the gluon and ghost
propagators in Euclidean Yang-Mills theory in the Landau gauge is analysed
within Zwanziger's local formulation of the Gribov horizon.Comment: Work presented at IX Hadron Physics and VII Relativistic Aspects of
Nuclear Physics, Angra dos Reis, RJ, Brazil, March 28 to April 03, 200
A study of the zero modes of the Faddeev-Popov operator in Euclidean Yang-Mills theories in the Landau gauge in d=2,3,4 dimensions
Examples of normalizable zero modes of the Faddeev-Popov operator in SU(2)
Euclidean Yang-Mills theories in the Landau gauge are constructed in d=2,3,4
dimensions.Comment: 18 pages. Text modifications. References added. Version accepted for
publication in the EPJ
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