Si. Vilchinsky et Pi. Fomin, THE TYPES OF ACOUSTIC EXCITATIONS IN 2-CONDENSATE RELATIVISTIC SUPERFLUID SYSTEMS, Low temperature physics, 24(1), 1998, pp. 5-8
The equations describing the propagation of acoustic waves in relativi
stic superfluid two-condensate systems are derived and solved. It is s
hown that the presence of an additional acoustic mode and two types of
waves of fourth sound is a peculiarity of the system under investigat
ion. (C) 1998 American Institute of Physics. [S1063-777X(98)00201-1].