3 research outputs found
Universality in the Three-Body Problem for 4He Atoms
The two-body scattering length a for 4He atoms is much larger than their
effective range r_s. As a consequence, low-energy few-body observables have
universal characteristics that are independent of the interaction potential.
Universality implies that, up to corrections suppressed by r_s/a, all
low-energy three-body observables are determined by a and a three-body
parameter \Lambda_*. We give simple expressions in terms of a and \Lambda_* for
the trimer binding energy equation, the atom-dimer scattering phase shifts, and
the rate for three-body recombination at threshold. We determine \Lambda_* for
several 4He potentials from the calculated binding energy of the excited state
of the trimer and use it to obtain the universality predictions for the other
low-energy observables. We also use the calculated values for one potential to
estimate the effective range corrections for the other potentials.Comment: 23 pages, revtex4, 6 ps figures, references added, universal
expressions update