Pseudopotential theory of interacting roton pairs in superfluid /sup 4/He

Journal Article · Sun Jan 01 00:00:00 EST 1984 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.29.102· OSTI ID:5171253

Bedell, K; Pines, D; Zawadowski, A

A configuration-space pseudopotential, which is closely related to that used by Aldrich and Pines to describe the effective interaction between background particles in /sup 3/He and /sup 4/He, is constructed and used to calculate the roton-roton scattering amplitude. From that amplitude we obtain a theory that is completely congruent with the roton-liquid theory of Bedell, Pines, and Fomin. We calculate two-roton bound states, roton-liquid parameters, and roton lifetimes, as well as information about the hybridization of the two-roton bound state with excitations of higher and lower energy. Excellent agreement between theory and experiment is obtained for the l = 2 bound state at zero pair momentum, the roton lifetime, the roton contribution to the normal-fluid viscosity and the normal-fluid density, and the temperature variation of the roton energy. The effective roton-roton coupling parameters at large pair momentum are found to be an order of magnitude larger than those for small or vanishing pair momentum. At SVP we find that a substantial number of two-roton bound states of varying symmetry exist for pair momentum up to approx.3 A/sup -1/; at standard pressure, however the roton-roton interaction for momenta approx.1 A/sup -1/ is found to become repulsive, so that both the l = 2 bound state at zero pair momentum and bound states at intermediate momenta are predicted to disappear under pressure.

• Research Organization: Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801; and Department of Physics, State University of New York at Stony Brook, Stony Brook, New York 11794
• DOE Contract Number: AC02-76ER13001
• OSTI ID: 5171253
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 29:1
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
HELIUM II
ROTONS
VISCOSITY
BOUND STATE
DENSITY
ENERGY LEVELS
LIFETIME
SUPERFLUIDITY
TEMPERATURE DEPENDENCE
EVEN-EVEN NUCLEI
FLUIDS
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
NUCLEI
PHYSICAL PROPERTIES
QUANTUM FLUIDS
QUASI PARTICLES
STABLE ISOTOPES
640450* - Fluid Physics- Superfluidity