MPEJ Volume 2, No.3, 9pp
Received: April 22, 1996, Accepted: May 23, 1996

G. Benfatto
Renormalization group approach to zero temperature Bose condensation

ABSTRACT:  We study the problem of Bose condensation at zero temperature
and weak coupling for a three dimensional system of bosons, interacting
with a repulsive short range potential, in the Bogoliubov approximation.
We prove that the properties of the model can be explained in terms of an
anomalous asymptotically free renormalization group flow and we show that
the two-point correlation function has the typical superfluid behaviour at
long wavelengths, as generally expected. The proof is, for the moment,
only at the level of perturbation theory in the running coupling constants.
We also obtain an expression for the sound speed, whose leading term
(when the coupling goes to zero) coincides with the sound speed in the
exactly soluble Bogoliubov model.