Nonextensive boson gas and specific heat of 4He superfluid

The temperature dependence of the heat capacity Cv of the boson gas is studied within the generalized quantum statistics. The generalized heat capacity (Cv)q is shown to increase strongly at all temperatures with increasing nonextensive parameter q. This (Cv)q behavior is used to reproduce the observed curve of Cv(T) of the liquid 4He(II) for the temperature range 1K⩽T⩽2.17K with particular q values. We obtain an almost linear T-dependence of parameter q which increases with increasing temperature from q≈0.5 at 1K to q≈1.35 at 2.17K. The observed 4He(I)−4He(II) transition temperature (2.17K) is also reproduced with q≈1.36.