Fluctuations of Bose-condensate in nonideal gas

Abstract

The canonical distribution with constraint is applied to the Bogolubov model of a nonideal Bose-gas. Two solutions of variational equations for Bose-condensate density and constraint parameter are found and treated as the “nontrivial” and “trivial” parts of the process of Bose-condensation. The corresponding branches of the spectrum are investigated. The heat capacity C V is considered with the help of the derived solutions for all the temperatures. The asymptotics of C V for the temperature close to zero and close to critical temperature T c below and above it are calculated.