Constant-Pressure Heat Capacity of a Bose Fluid Immediately Above the lambda Point

The heat capacity C-p of a Bose fluid immediately above its 2 point is shown to depend solely on the nature of its low-momentum quasiparticles. If these quasiparticles are only weakly interacting, then it is possible to specify uniquely the limiting behavior C-P(T -> T-lambda(+)) from a knowledge of the quasiparticle energy-momentum relation omega'(k) in the low-momentum limit. Thus, phonon-type behavior is shown to result in a finite cusp for C-P(T-lambda(+)). The relevance of these results to liquid He-4 is discussed.