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DY: Dynamik und Statistische Physik

DY 35: Critical phenomena and phase transitions I

DY 35.1: Vortrag

Mittwoch, 26. März 2003, 14:30–14:45, G\"OR/229

Bose-Einstein Condensation Transition Temperature Shift for a Homogeneous Weakly Interacting Bose Gas Through Six Loops — •Boris Kastening — Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin

There exists a host of different theoretical claims about the nature and size of the shift of the transition temperature for Bose-Einstein condensation in a homogenous weakly interacting gas of Bosons. Recently, it was established that in leading order the transition temperature increases linearly with the interaction strength parameterized in terms of the scattering length [1]. Here we present the results of a computation of the related numerical coefficient. We have performed a six-loop perturbative computation combined with resummation utilizing variational perturbation theory. Resummation is necessary, since we have to go to the critical regime, which is equivalent to the limit of large effective coupling. We extend existing five-loop calculations [2] to six loops [3].

[1] G.Baym, J.-P.Blaizot, M.Holzmann, F.Laloë, D.Vautherin, Phys.Rev.Lett.83 (1999) 1703 [cond-mat/9905430].

[2] F.F.de Souza Cruz, M.B.Pinto, R.O.Ramos, P.Sena, Phys.Rev.A 65 (2002) 053613 [cond-mat/0112306]; E.Braaten, E.Radescu, cond-mat/0206186; H.Kleinert, cond-mat/0210162.

[3] B.Kastening, in preparation.