O. Oliveira

Indirect lattice evidence for the refined Gribov-Zwanziger formalism and the gluon condensate in the Landau gauge

We consider the gluon propagator D(p{sup 2}) at various lattice sizes and spacings in the case of pure SU(3) Yang-Mills gauge theories using the Landau gauge fixing. We discuss a class of fits in the infrared region in order to (in)validate the tree level analytical prediction in terms of the (refined) Gribov-Zwanziger framework. It turns out that an important role is played by the presence of the widely studied dimension two gluon condensate . Including this effect allows to obtain an acceptable fit around 1 to 1.5 GeV, while corroborating the refined Gribov-Zwanziger prediction for the gluon propagator. We also discuss the infinite volume extrapolation, leading to the estimate D(0)=8.3{+-}0.5 GeV{sup -2}. As a by-product, we can also provide the prediction {approx_equal}3 GeV{sup 2} obtained at the renormalization scale {mu}=10 GeV.

The lattice Landau gauge gluon propagator: lattice spacing and volume dependence

The interplay between the finite volume and finite lattice spacing is investigated using lattice QCD simulations to compute the Landau gauge gluon propagator. Comparing several ensembles with different lattice spacings and physical volumes, we conclude that the dominant effects, in the infrared region, are associated with the use of a finite lattice spacing. The simulations show that decreasing the lattice spacing, while keeping the same physical volume, leads to an enhancement of the infrared gluon propagator. In this sense, the data from

Gribov copies, lattice QCD and the gluon propagator

\beta=5.7

Does the lattice zero-momentum gluon propagator for pure-gauge SU(3) Yang-Mills theory vanish in the infinite-volume limit?

simulations, which uses an

On the quark-gluon vertex and quark-ghost kernel: combining lattice simulations with Dyson-Schwinger equations

a \approx 0.18

Nontrivial ghost-gluon vertex and the match of RGZ, DSE and lattice Yang-Mills propagators

fm, provides a lower bound for the infinite volume propagator.

Lattice gluon and ghost propagators and the strong coupling in pure SU(3) Yang-Mills theory: Finite lattice spacing and volume effects

We address the problem of Gribov copies in lattice QCD. The gluon propagator is computed, in the Landau gauge, using 302 (� = 5.8) 12 4 configurations gauge fixed to different copies. The results of the simulation shows that: i) the effect of Gribov copies is small (less than 10%); ii) Gribov copies change essentially the lowest momenta components (q < 2.6 GeV); iii) within the statistical accuracy of our simulation, the effect of Gribov copies is resolved if statistical errors are multiplied by a factor of two or three. Moreover, when modelling the gluon propagator, different sets of Gribov copies produce different sets of parameters not, necessarily, compatible within one standard deviation. Finally, our data supports a gluon propagator which, for large momenta, behaves like a massive gluon propagator with a mass of 1.1 GeV.

Gluon screening mass at finite temperature from the Landau gauge gluon propagator in lattice QCD

The Cucchieri-Mendes bounds for the gluon propagator are discussed for the four dimensional pure-gauge SU(3) theory. Assuming a pure power law dependence on the inverse of the lattice volume, the lattice data gives a vanishing zero-momentum gluon propagator in the infinite-volume limit in agreement with the Gribov-Zwanziger horizon condition but contradicting the SU(2) analysis. The results are robust against variations of the lattice volumes and corrections to the power law. Our analysis considers also more general ansatze that, although not conclusive, open the possibility of having D(0){ne}0 in the infinite-volume limit. A solution to this puzzle requires further investigations.

The lattice gluon propagator in renormalizable

A bstractWe investigate the dressed quark-gluon vertex combining two established non-perturbative approaches to QCD: the Dyson-Schwinger equation (DSE) for the quark propagator and lattice-regularized simulations for the quark, gluon and ghost propagators. The vertex is modeled using a generalized Ball-Chiu ansatz parameterized by a single form actor

\xi

{{\widetilde{X}}_0}