5,723 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.
Massive photons and Dirac monopoles: electric condensate and magnetic confinement
We use the generalized Julia-Toulouse approach (GJTA) for condensation of
topological currents (charges or defects) to argue that massive photons can
coexist consistently with Dirac monopoles. The Proca theory is obtained here
via GJTA as a low energy effective theory describing an electric condensate and
the mass of the vector boson is responsible for generating a Meissner effect
which confines the magnetic defects in monopole-antimonopole pairs connected by
physical open magnetic vortices described by Dirac brane invariants, instead of
Dirac strings.Comment: 6 pages, version accepted for publication in Physics Letters
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
Gribov horizon and BRST symmetry: a pathway to confinement
We summarize the construction of the Gribov-Zwanziger action and how it leads
to a scenario which explains the confinement of gluons, in the sense that the
elementary gluon excitations violate positivity. Then we address the question
of how one can construct operators within this picture whose one-loop
correlation functions have the correct analytic properties in order to
correspond to physical excitations. For this we introduce the concept of
i-particles.Comment: 5 pages, proceedings of XII Mexican Workshop on Particles and Fields
200
An all-order proof of the equivalence between Gribov's no-pole and Zwanziger's horizon conditions
The quantization of non-Abelian gauge theories is known to be plagued by
Gribov copies. Typical examples are the copies related to zero modes of the
Faddeev-Popov operator, which give rise to singularities in the ghost
propagator. In this work we present an exact and compact expression for the
ghost propagator as a function of external gauge fields, in SU(N) Yang-Mills
theory in the Landau gauge. It is shown, to all orders, that the condition for
the ghost propagator not to have a pole, the so-called Gribov's no-pole
condition, can be implemented by demanding a nonvanishing expectation value for
a functional of the gauge fields that turns out to be Zwanziger's horizon
function. The action allowing to implement this condition is the
Gribov-Zwanziger action. This establishes in a precise way the equivalence
between Gribov's no-pole condition and Zwanziger's horizon condition.Comment: 11 pages, typos corrected, version accepted for publication in Phys.
Lett.
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