Freiburg 2008 – scientific programme

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T: Fachverband Teilchenphysik

T 22: Quantenfeldtheorie II

T 22.3: Talk

Friday, March 7, 2008, 14:30–14:45, KGI-HS 1016

Integrating out the Dirac sea: Effective field theory approach to exactly solvable four-fermion models — •Felix Karbstein and Michael Thies — Institut für Theoretische Physik III, Universität Erlangen-Nürnberg, D-91058 Erlangen

We use 1+1 dimensional large N Gross-Neveu models as a laboratory to derive microscopically effective Lagrangians for positive energy fermions only. When applied to baryons, the Euler-Lagrange equation for these effective theories assumes the form of a non-linear Dirac equation. Its solution reproduces the full semi-classical results including the Dirac sea to any desired accuracy. Dynamical effects from the Dirac sea are encoded in higher order derivative terms and multi-fermion interactions with perturbatively calculable, finite coefficients. Characteristic differences between models with discrete and continuous chiral symmetry are observed and clarified.