J.-B. Bru and V.A. Zagrebnov
Large Deviations in the Superstable Weakly Imperfect Bose Gas
(484K, Postscript)
ABSTRACT. The superstable Weakly Imperfect Bose Gas (WIBG) was originally derived to solve
the inconsistency of the Bogoliubov theory of superfluidity. Its
grand-canonical thermodynamics was recently solved but not at point of the
(first order) phase
transition. This paper proposes to close this gap by using the large
deviations formalism and in particular the analysis of the Kac distribution function.
It turns out that, as a function of the chemical
potential, the discontinuity of the Bose condensate density at the phase
transition point disappears as a function of the particle density. Indeed, the
Bose condensate continuously starts at the first critical particle density and
progressively grows but the free-energy per particle stays constant until the
second critical density is reached. At higher particle densities, the Bose
condensate density as well as the free-energy per particle both increase monotonously.