Visco-elastic spectra of a dilute Bose fluid

A recently developed local-density current functional formalism for confine d Bose-condensed superfluids requires visco-elastic spectra which are defin ed through a finite-frequency extension of the dissipative coefficients ent ering the linearized hydrodynamic equations of the two-fluid model. We eval uate these spectra for a superfluid with contact interactions in the collis ionless regime at finite temperature, by working to first order beyond the Bogolubov approximation. We find that within this approximation all the vis co-elastic spectra take the same Value aside from simple multiplicative fac tors. (C) 1999 Elsevier Science B.V. All rights reserved.