Relation between the bound state radius and the scattering length: Relativistic effects

Relativistic effects on the relation between the root-mean-square radius rD of the bound state and the scattering length a are examined for models which simulate the triplet S state of the two-nucleon system. Two models are considered; one is based on the one-body Dirac equation and the other on the two-body Dirac equation. The relation is expressed as (rD/a)2=(c0+c1x1+c2x2+...)/8, where x==αr0; α is related to the binding energy and r0 is the …