Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 9: Solids at Low Temperature - Quantum Liquids, Bose-Einstein Condensates, Ultracold Atoms, ...

TT 9.2: Talk

Friday, March 4, 2005, 17:30–17:45, TU H3027

1/N-Expansion for Interacting Bose Gas — •Flavio Nogueira¹ and Axel Pelster² — ¹Institut für Theoretische Physik, Freie Universität Berlin, Berlin, Germany — ²Fachbereich Physik, Universität Duisburg-Essen, Essen, Germany

We study the interacting Bose gas by treating a field-theoretic model with N complex fields via a 1/N expansion. The resulting excitation spectrum follows from solving a self-consistent equation which contains a temperature-dependent effective interaction. Thermal fluctuations generate an anomalous scaling behavior in the excitation spectrum which leads to a second-order phase transition. Finally, we determine within our 1/N approach the temperature dependence of both the condensate density and the superfluid density.