Related papers: ILM gluons in perturbative QCD
Landau gauge longitudinal and transverse gluon propagators are studied in lattice QCD with gauge group $SU(2)$ at varying temperature and quark density. In particular, it is found that the longitudinal propagator decreases with increasing…
We include instanton effects in QCD sum rules for coupled scalar glueballs and mesons. We find a light glueball/sigma as in earlier studies without instantons, but in a lattice-type pure instanton model the light glueball/sigma is not…
Comparison of two appropriately chosen screening masses of colour singlet operators in the pure glue QCD plasma indicates that at sufficiently high temperature it contains a weakly-interacting massive quasi-particle with the quantum numbers…
We investigate the impact of instantons on scalar glueball properties in a largely model-independent analytical approach based on the instanton-improved operator product expansion (IOPE) of the $0^{++}$ glueball correlator. The instanton…
We present non-perturbative first-principle results for quark-, gluon- and meson $1$PI correlation functions of two-flavour Landau-gauge QCD in the vacuum. These correlation functions carry the full information about the theory. They are…
The instanton vacuum provides an effective description of chiral symmetry breaking by local topological fluctuations of the gauge fields, as observed in lattice QCD simulations. The resulting effective dynamics at momenta below $1/\bar\rho…
We review recent work on the effects of quark loops on the gluon propagator in the Landau gauge, relying mainly on the Schwinger-Dyson equations that describe the two-point sector of QCD. Particularly important in this context is the…
There is a good deal of current interest in the condensate A^2 which has been seen to play an important role in calculations which make use of the operator product expansion. That development has led to the publication of a large number of…
The Kugo-Ojima confinement criterion and its relation to the infrared behaviour of the gluon and ghost propagators in Landau gauge QCD are reviewed. The realization of this confinement criterion (which in Landau gauge relates to Zwanziger's…
Based on both the constituent quark picture and the instanton model for QCD vacuum, we calculate the unpolarized and polarized gluon distributions in the constituent quark and in the nucleon. Our approach consists of the two main steps. At…
Soft gluon radiation induced by multiple scattering of a fast quark or gluon propagating through QCD matter is discussed. After revisiting the Landau-Pomeranchuk-Migdal effect in QED we show that large formation times of bremsstrahlung…
In the Operator Product Expansion (OPE) of hard scattering amplitudes, the twist-3 operators describe local colored Lorentz forces acting on a quark, thereby providing a measure of the strength of the gluon fields. Its value is directly…
We investigate the temperature dependence of the instanton content of gluon fields and their contribution to quark correlation using quenched lattice QCD and the cooling method. We found a suppression of the topological susceptibility at…
We propose to realize a mass gap in QCD not imposing the transversality condition on the full gluon self-energy, while preserving the color gauge invariance condition for the full gluon propagator. Since due to color confinement the gluon…
We study the scattering of small color dipoles (e.g., heavy quarkonium states) at low energies. We find that even though the couplings of color dipoles to the gluon field can be described in perturbation theory, at large distances the…
It has long been known that the gluon propagator in Landau-gauge QCD exhibits a mass gap; and its emergence has been ascribed to the action of the Schwinger mechanism in the gauge sector of QCD. In the present work, we relate this property…
Perturbative calculations of the static QCD potential have the $u=3/2$ renormalon uncertainty. In the multipole expansion performed within pNRQCD, this uncertainty at LO is known to get canceled against the ultrasoft correction at NLO. To…
In Landau gauge QCD the infrared behavior of the propagator of transverse gluons can be analytically determined to be a power law from Dyson-Schwinger equations. This propagator clearly shows positivity violation, indicating the absence of…
We compute the spectrum of gluons emitted by a highly energetic quark inside a flowing QCD medium, focusing on the soft gluon limit at first order in the opacity expansion. Specifically, we derive the leading energy-suppressed corrections…
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,…