Sergei N. Nedelko

Infrared behavior and fixed points in Landau-gauge QCD.

We investigate the infrared behavior of gluon and ghost propagators in Landau-gauge QCD by means of an exact renormalization group equation. We explain how, in general, the infrared momentum structure of Green functions can be extracted within this approach. An optimization procedure is devised to remove residual regulator dependences. In Landau-gauge QCD this framework is used to determine the infrared leading terms of the propagators. The results support the Kugo-Ojima confinement scenario. Possible extensions are discussed.

Impact of the strong electromagnetic field on the QCD effective potential for homogeneous Abelian gluon field configurations

The one-loop quark contribution to the QCD effective potential for the homogeneous Abelian gluon field in the presence of an external strong electromagnetic field is evaluated. The structure of extrema of the potential as a function of the angles between chromoelectric, chromomagnetic, and electromagnetic fields is analyzed. In this setup, the electromagnetic field is considered as an external one while the gluon field represents domain structured nonperturbative gluon configurations related to the QCD vacuum in the confinement phase. Two particularly interesting gluon configurations, (anti-)self-dual and crossed orthogonal chromomagnetic and chromoelectric fields, are discussed specifically. Within this simplified framework it is shown that the strong electromagnetic fields can play a catalyzing role for a deconfinement transition. At the qualitative level, the present consideration can be seen as a highly simplified study of an impact of the electromagnetic fields generated in relativistic heavy ion collisions on the strongly interacting hadronic matter.

Confinement signatures in Landau gauge QCD

We summarise an analysis of the infrared regime of Landau gauge QCD by means of a flow equation approach. The infrared behaviour of gluon and ghost propagators is evaluated. The results provide further evidence for the Kugo‐Ojima confinement scenario. We also discuss their relation to results obtained with other functional methods as well as the lattice.

CP-violating theta parameter in the domain model of the QCD vacuum

A nonzero

Spectral density in the resonance region and analytic confinement

CP

Infrared QCD and the Renormalisation Group

-violating

Pion transition form factor in the domain model of QCD vacuum

\ensuremath{\theta}

Domain wall network as QCD vacuum: confinement, chiral symmetry, hadronization

parameter is treated in the domain model which assumes a clusterlike vacuum structure whose units are characterized, in particular, by a topological charge which is not necessarily an integer number. In the present paper we restrict consideration to rational values of the charge. The model has previously been shown to manifest confinement, spontaneous chiral symmetry breaking and the absence of an axial

Realization of chiral symmetry in the domain model of QCD

U(1)

Poincare recurrence theorem and the strong CP problem

Goldstone boson. We find that the specific structure of the minima of the free energy density of the domain ensemble forces a