Lower bound to the reciprocal of the scattering length: II

Abstract

It is shown that, for the scattering of zero-energy particles by a compound system, Kohn's variational method used in conjunction with `inappropriately normalized' trial functions provides an absolute lower bound to the reciprocal of the scattering length in the following cases: (i) there exists no composite bound state and the Born approximation to the scattering length aB < 0; (ii) there exists one composite bound state, aB < 0 and the exact scattering length a >or= 0; (iii) there exists no composite bound state and a >or= 0.