Description of composite bosons in discrete models

PAULA CÉSPEDES; ELENA RUFEIL FIORI; P. ALEXANDER BOUVRIE; ANA P. MAJTEY; CECILIA CORMICK

PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS

AMER PHYSICAL SOC

Año: 2019 vol. 100 p. 12309 - 12318

1050-2947

The understanding of the behavior of systems of identical composite bosons has progressed significantly in connection with the analysis of the entanglement between constituents and the development of coboson theory.The basis of these treatments is a coboson ansatz for the ground state of a system of N pairs, stating that in appropriate limits this state is well approximated by the account of Pauli exclusion in what would otherwise bethe product state of N independent pairs, each described by the single-pair ground state. In this work we study the validity of this ansatz for particularly simple problems, and show that short-range attractive interactions in very dilute limits and a single-pair ground state with very large entanglement are not enough to render the ansatz valid. On the contrary, we find that the dimensionality of the problem plays a crucial role in the behavior of the many-body ground state.