352 research outputs found
Nonperturbative ghost dynamics in the maximal Abelian gauge
We construct the effective potential for the ghost condensate
in the maximal Abelian gauge. This condensate is an
order parameter for a global continuous symmetry, which is spontaneously broken
since a nonvanishing value of lowers the vacuum energy.
The associated Goldstone mode turns out to be unphysical.Comment: 16 pages. v2: version accepted for publication in JHE
Dimension two gluon condensates in a variety of gauges and a gauge invariant Yang-Mills action with a mass
We give a short overview of our work concerning the dimension two operator
A^2 in the Landau gauge and its generalizations to other gauges. We conclude by
discussing recent work that leads to a renormalizable gauge invariant action
containing a mass parameter, based on the operator F 1/D^2 F.Comment: 4 pages. espcrc2.sty is used. Talk given at "13th International
Conference In QCD (QCD 06), 3-7 Jul 2006, Montpellier, France
Renormalization properties of the mass operator A^2 in three dimensional Yang-Mills theories in the Landau gauge
Massive renormalizable Yang-Mills theories in three dimensions are analysed
within the algebraic renormalization in the Landau gauge. In analogy with the
four dimensional case, the renormalization of the mass operator A^2 turns out
to be expressed in terms of the fields and coupling constant renormalization
factors. We verify the relation we obtain for the operator anomalous dimension
by explicit calculations in the large N_f. The generalization to other gauges
such as the nonlinear Curci-Ferrari gauge is briefly outlined.Comment: 15 pages, 3 figure
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.
(Lattice) Propagators and Extraction of Spectral Densities
In this proceeding, we explain a few steps for an alternative extraction of
the spectral density of a two-point function (propagator) based on a discrete
set of data points. We present a so-called Tikhonov regularization of this
particular inverse problem. We test it on 2 cases: lattice 0++} glueball data
and mock gluon data.Comment: 8 pages, 4 figures. Proceedings of Xth Quark Confinement and the
Hadron Spectrum, October 8-12, 2012, TUM Campus Garching, Munich, German
Comments on the Chern-Simons photon term in the QED description of graphene
We revisit the Coleman-Hill theorem in the context of reduced planar QED.
Using the global U(1) Ward identity for this non-local but still gauge
invariant theory, we can confirm that the topological piece of the photon
self-energy at zero momentum does not receive further quantum corrections apart
from the potential one-loop contribution, even when considering the Lorentz
non-invariant case due to the Fermi velocity . This is of relevance to
probe possible time parity odd dynamics in a planar sheet of graphene which has
an effective description in terms of -dimensional planar reduced QED.Comment: New section added, published versio
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
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
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.
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