Berlin 2008 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 8: Superfluidity and Bose Einstein Condensation

DY 8.3: Vortrag

Montag, 25. Februar 2008, 17:30–17:45, MA 001

Functional renormalization group analysis of the interacting Bose gas in the symmetry broken phase — •Andreas Sinner, Nils Hasselmann, and Peter Kopietz — Institut für Theoretische Physik, Universität Frankfurt, Max-von-Laue Str.1, 60438 Frankfurt

We investigate the small frequency and momentum structure of the weakly interacting Bose gas in 1≤ D≤ 3 within a functional renormalization group approach. Using a variant of the local potential approximation, the U(1) symmetry is automatically obeyed and our approach allows to go beyond the Bogoliubov theory in a consistent manner. The flow equations are derived within a derivative approximation of the effective action up to second order in spatial and temporal variables and investigated numerically. We present further an approach which goes beyond the derivative approximation of the functional renormalization group. It allows to calculate corrections to the Bogoliubov spectrum and to investigate the damping of quasiparticles also at finite momenta.