T-matrix and effective scattering in spin-polarized atomic deuterium (↓D)

The Galitskii-Migdal-Feynman (GMF) formalism is applied to spin-polarized atomic deuterium (↓D). The effective scattering length is calculated from the GMF T-matrix, which is essentially the effective scattering amplitude dependent on the medium. It is found that the S-wave effective scattering length for ↓D2 and ↓D3 varies discontinuously from negative to positive values at some critical density. This indicates a crossover from a dimer-less regime to a regime with dimers. In addition, it is confirmed that ↓D1 remains a gas down to zero Kelvin. Finally, the binding energy of the weakly bound dimers in both species ↓D2 and ↓D3 is computed. For completeness as well as for comparison purposes, the scattering length in the free-scattering limit is also calculated and it is found to be in a good agreement with previous calculations.