The transition temperature of the dilute interacting Bose gas

Gordon Baym, Jean-Paul Blaizot, Markus Holzmann, Franck Laloë, Dominique Vautherin

Published 1999-05-29, updated 1999-08-08Version 3

We show that the critical temperature of a uniform dilute Bose gas must increase linearly with the s-wave scattering length describing the repulsion between the particles. Because of infrared divergences, the magnitude of the shift cannot be obtained from perturbation theory, even in the weak coupling regime; rather, it is proportional to the size of the critical region in momentum space. By means of a self-consistent calculation of the quasiparticle spectrum at low momenta at the transition, we find an estimate of the effect in reasonable agreement with numerical simulations.