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We solve numerically the Schwinger-Dyson (SD hereafter) ghost equation in the Landau gauge for a given gluon propagator finite at k=0 (alpha_gluon=1) and with the usual assumption of constancy of the ghost-gluon vertex ; we show that there…

High Energy Physics - Phenomenology · Physics 2010-03-19 Ph. Boucaud , J-P. Leroy , A. Le Yaouanc , J. Micheli , O. Pene , J. Rodriguez--Quintero

We report on the progress we made in studying the infrared behavior of the ghost and gluon dressing functions in Landau gauge. Related to this we also investigate a running coupling given in terms of those functions and compare our results…

High Energy Physics - Lattice · Physics 2010-12-13 A. Sternbeck , E. -M. Ilgenfritz , M. Mueller-Preussker , A. Schiller

In a functional approach to QCD the infrared behaviour of Landau gauge Green functions is investigated. It can be proven that the ghost Dyson-Schwinger equation implies the Gribov-Zwanziger horizon condition. Its relation to the Kugo-Ojima…

High Energy Physics - Phenomenology · Physics 2008-11-26 Reinhard Alkofer

A truncation scheme for the Dyson-Schwinger equations of QCD in Landau gauge is presented which implements the Slavnov-Taylor identities for the 3-point vertex functions. Neglecting contributions from 4-point correlations such as the…

High Energy Physics - Phenomenology · Physics 2009-10-30 Lorenz von Smekal , Andreas Hauck , Reinhard Alkofer

Truncated Dyson-Schwinger equations represent finite subsets of the equations of motion for Green's functions. Solutions to these non-linear integral equations can account for non-perturbative correlations. A closed set of coupled…

High Energy Physics - Phenomenology · Physics 2009-10-31 Andreas Hauck , Lorenz von Smekal , Reinhard Alkofer

A truncation scheme for the Dyson-Schwinger equations of QCD in Landau gauge is presented which implements the Slavnov-Taylor identities for the 3-point vertex functions. Neglecting contributions from 4-point correlations such as the…

High Energy Physics - Phenomenology · Physics 2007-05-23 Andreas Hauck , Reinhard Alkofer , Lorenz von Smekal

A numerical study of the ghost Dyson-Schwinger equation in Coulomb gauge is performed and solutions for the ghost propagator found. As input, lattice results for the spatial gluon propagator are used. It is shown that in order to solve…

High Energy Physics - Theory · Physics 2010-12-24 Peter Watson , Hugo Reinhardt

We summarise results on the infrared behaviour of Landau gauge QCD from the Green's functions approach and lattice calculations. Approximate, nonperturbative solutions for the ghost, gluon and quark propagators as well as first results for…

High Energy Physics - Phenomenology · Physics 2008-11-26 C. S. Fischer , F. Llanes-Estrada , R. Alkofer

The results of Coulomb gauge and Landau gauge lattice QCD simulation do not agree completely with continuum theory. There are indications that the ghost propagator in the infrared region is not purely color diagonal as in high energy…

High Energy Physics - Lattice · Physics 2009-01-13 Sadataka Furui

In a previous paper, we presented solution to the Slavnov--Taylor identity for the QCD effective action, and argued that the action terms containing (anti)ghost fields are unique. These terms have the same form as those in the classical…

High Energy Physics - Phenomenology · Physics 2009-11-07 G. Cvetic , I. Kondrashuk , I. Schmidt

In this work we use two different but complementary approaches in order to study the ghost propagator of a pure SU(3) Yang-Mills theory quantized in the linear covariant gauges, focusing on its dependence on the gauge-fixing parameter $\xi$…

High Energy Physics - Phenomenology · Physics 2015-04-16 A. C. Aguilar , D. Binosi , J. Papavassiliou

We investigate the infrared behaviour of gluon and ghost propagators in Landau gauge QCD by means of an exact renormalisation group equation. We explain how, in general, the infrared momentum structure of Green functions can be extracted…

High Energy Physics - Theory · Physics 2009-11-10 Jan M. Pawlowski , Daniel F. Litim , Sergei Nedelko , Lorenz von Smekal

The coupled Dyson-Schwinger equations for the gluon and ghost propagators are investigated in the Landau gauge using a two-loop improved truncation that preserves the multiplicative renormalizability of the propagators. In this truncation…

High Energy Physics - Phenomenology · Physics 2009-01-14 J. C. R. Bloch

Infrared finite solutions for the gluon propagator of pure QCD are obtained from the gauge-invariant non-linear Schwinger-Dyson equation formulated in the Feynman gauge of the background field method. These solutions may be fitted using a…

High Energy Physics - Phenomenology · Physics 2008-11-26 A. C. Aguilar , J. Papavassiliou

We fix exactly and uniquely the infrared structure of the full gluon propagator in QCD, not solving explicitly the corresponding dynamical equation of motion. By construction, this structure is an infinite sum over all possible severe…

High Energy Physics - Phenomenology · Physics 2009-11-10 V. Gogohia

We show that the application of a novel gauge invariant truncation scheme to the Schwinger-Dyson equations of QCD leads, in the Landau gauge, to an infrared finite gluon propagator and a divergent ghost propagator, in qualitative agreement…

High Energy Physics - Phenomenology · Physics 2009-08-31 A. C. Aguilar , D. Binosi , J. Papavassiliou

We exploit the Ward-Slavnov-Taylor identity relating the 3-gluons to the ghost-gluon vertices to conclude either that the ghost dressing function is finite and non vanishing at zero momentum while the gluon propagator diverges (although it…

High Energy Physics - Phenomenology · Physics 2010-03-19 Ph. Boucaud , J. P. Leroy , A. Le Yaouanc , A. Y. Lokhov , J. Micheli , O. Pène , J. Rodríguez-Quintero , C. Roiesnel

The effective gluon propagator constructed with the pinch technique is governed by a Schwinger-Dyson equation with special structure and gauge properties, that can be deduced from the correspondence with the background field method. Most…

High Energy Physics - Phenomenology · Physics 2008-11-26 A. C. Aguilar , J. Papavassiliou

Nonperturbative properties of gluons are studied in SU(3) lattice QCD at the quenched level. The first subject is a functional-form analysis of the gluon propagator $D_{\mu\nu}^{ab}(x)$ in the Landau gauge. We find that the gluon propagator…

High Energy Physics - Lattice · Physics 2011-07-14 Hideo Suganuma , Takumi Iritani , Arata Yamamoto , Hideaki Iida

We establish exactly and uniquely the infrared structure of the full gluon propagator in QCD, not solving explicitly the corresponding dynamical equation of motion. By construction, this structure is an infinite sum over all possible severe…

High Energy Physics - Phenomenology · Physics 2007-05-23 V. Gogohia