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HK: Hadronen und Kerne
HK 68: Structure of Baryons, Mesons X, Theory
HK 68.1: Group Report
Thursday, March 19, 1998, 14:00–14:30, J
Nichtperturbative Flussgleichungen im Konstituentenquark-Modell — •B.-J. Schaefer and H.-J. Pirner — Institut f"ur Theoretische Physik, Universit"at Heidelberg, Philosophenweg 19, D-69120 Heidelberg
We derive non-perturbative flow equations within an effective constituent quark model for Nf=2. We employ Heat-Kernel methods to achieve a renormalization group improved effective potential. We study the evolution of quantities like the minimum of the potential with respect to a momentum scale k at vanishing temperature. At the first stage we omit corrections coming from the anomalous dimension. This investigation is extrapolated to finite temperature, where we find a second order phase transition in the chiral limit at Tc ≈ 90 MeV. Due to a smooth decoupling of massive modes, we can directly link the low-temperature four-dimensional theory to the three-dimensional high-temperature theory and can determine universal critical exponents.