Reinhard Alkofer

A covariant model for dynamical chiral-symmetry breaking in QCD

Abstract Assuming a 1/ k 4 behaviour of the gluon propagator for small euclidean momenta we are investigating the infrared properties of the quark propagator and the quark-gluon vertex function using a covariant model motivated by QCD and its Slavnov-Taylor identities. Keeping the known high-energy behaviour of the gluon propagator we discuss in detail the renormalization of the Dyson-Schwinger equation. Numerical results are given for the quark propagator, the quark condensate and the pion decay constant.

The chiral soliton of the Nambu-Jona-Lasinio model with ϱ-meson

The baryon number one soliton of the NJL model is investigated. The Euclidian effective action is regularized using Schwingers proper time method. Numerical results for the static soliton energy are presented for the cases without and with vector and axialvector fields. It is found that the baryon number is carried by the polarized Dirac sea of the quarks if the

A model for the chiral phase transition in QCD

a_1

Kugo-Ojima confinement and QCD Green's functions in covariant gauges

meson is included in contrast to the case without

KUGO-OJIMA CONFINEMENT CRITERION, ZWANZIGER-GRIBOV HORIZON CONDITION, AND INFRARED CRITICAL EXPONENTS IN LANDAU GAUGE QCD

a_1

The Infrared Behavior of QCD Green's Functions

where the baryon number resides on valence quarks. Thus the model strongly supports the picture of the baryon as a topological soliton of the meson fields. Including the

Instanton-induced flavour mixing in mesons

\omega

Chiral quark dynamics

vector meson leads to a non--vanishing imaginary part of the Euclidian effective action even for static solitons. Leaving the chiral circle, i.e.\ including the isoscalar scalar meson, the soliton first seems unstable. However, we demonstrate that a

Temperature dependence of η and η′ production in heavy-ion collisions

\phi ^4

The strong running coupling from an approximate gluon Dyson-Schwinger equation

term stabilizes the soliton. Finally, the self--consistent two--flavor chiral soliton is embedded in the SU(3) flavor group and collectively quantized. The predicted mass splittings for the low--lying baryons with different hypercharge are in excellent agreement with the experimental data if the physical value for the kaon decay constant is substituted.