Göttingen 1997 – scientific programme

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HK: Hadronen und Kerne

HK 55: Struktur von Baryonen und Mesonen VI

HK 55.3: Talk

Wednesday, March 26, 1997, 18:00–18:15, HS I

Restoration of chiral symmetry beyond instantaneous approximation — •Monika Schefzik, Kurt Langfeld, and Hugo Reinhardt — Institut für Theoretische Physik, Univ. Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen

Strongly coupled QED with fermions and a scalar field is used as a toy model to investigate the restoration of chiral symmetry at finite density. The Schwinger-Dyson equation approach is employed to study the Higgs phase of the model, and, in particular, the finite density phase transition from the chirally broken phase to a phase where chiral symmetry is restored. The full numerical treatment reveals a first order phase transition at small photon masses, whereas this transition is second order at large masses. Since the instantaneous approximation always predicts a second order transition, it provides reliable results only in the case of a large photon mass. We therefore propose a modified Landau approximation. We find that the results which were obtained within this approxiamtion are in excelllent agreement with those of the full numerical treatment also at small photon masses.