Superfluid 4He: brief notes on collective energy excitations and specific heat.

Abstract

These brief notes about some amazing properties of the helium superfluid have been written to graduate and postgraduate students of physics. We have estimated some collective energy excitations (linear vortices, energy spectrum of the quasiparticles and solitons) and calculated the specific heat of the superfluid helium assuming that the transition superfluid liquid → liquid is an order-disorder transition