New mechanism for the enhancement of sd dominance in interacting boson models

We introduce an exactly solvable model for interacting bosons that extend u p to high spin and interact through a repulsive pairing force. The model ex hibits a phase transition to a state with almost complete sd dominance. The repulsive pairing interaction that underlies the model has a natural micro scopic origin in the Pauli exclusion principle between constituent nucleons . As such, repulsive pairing between bosons seems to provide a new mechanis m for the enhancement of sd dominance, giving further support for the valid ity of the sd interacting boson model.