
VOLUME 27 (1978)  ISSUE 11 
PAGE 658

Properties of the endpoint of a multiphonon spectrum
lordanskii S.V., Pitaevskii L.P.
The properties of the energy spectrum of liquid helium near the sound line € = up are investigated. At Τ = 0 it is possible to impart to helium energy and momentum only in the region on the (e, p) plane above this line, and as this line is approached the energy should be partitioned among an ever increasing larger number of phonons. The probability of this process, i.e., the imaginary part of the corresponding Green's function, is proportional to exp(—5и In n), where η is the number of the produced phonons.

