Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: Correlated Electrons - Poster Session
TT 20.84: Poster
Mittwoch, 28. März 2007, 14:00–17:45, Poster A
Low-density expansion for the two-dimensional electron gas — •Francesca Sauli and Peter Kopietz — Institut für Theoretische Physik, J.W. Goethe Universität, Frankfurt am Main
We show that in two dimensions (2D) a systematic expansion of the self-energy and the effective interaction of a dilute electron gas in powers of the two-body T-Matrix T0 can be generated from an exact hierarchy of the functional renormalization group equations for one-particle irreducible vertices using the chemical potential as flow parameter. Due to the interference of particle-particle and particle-hole channels at order T02, in 2D the ladder approximation for the self-energy is not reliable beyond the leading order in T0. We also discuss two-body scattering in vacuum in arbitrary dimensions from the renormalization group point of view and argue that the singular interaction proposed by Anderson [Phys. Rev. Lett. 65, 2306 (1990)] cannot be ruled out on the basis of the ladder approximation.