ar X iv : c on d - m at / 0 10 21 65 v 1 9 F eb 2 00 1 Theoretical study of the dynamic structure factor of superfluid 4 He
نویسندگان
چکیده
We study the dynamic structure factor S(q, ω) of superfluid 4 He at zero temperature in the roton momentum region and beyond using field-theoretical Green's function techniques. We start from the Gavoret-Nozì eres two-particle propagator and introduce the concept of quasi-particles. We treat the residual (weak) interaction between quasiparticles as being local in coordinate space and weakly energy dependent. Our quasiparticle model explicitly incorporates the Bose-Einstein condensate. A complete formula for the dynamic susceptibility , which is related to S (q , ω) , is derived. The structure factor is numerically calculated in a self-consistent way in the special case of a momentum independent interaction between quasiparticles. Results are compared with experiment and other theoretical approaches .
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