One-Dimensional Two-Component Bosons with Attractive Interaction

The Bethe-ansatz method is used to solve one-dimensional two-component
bosons with a δ-function potential considering the negative coupling constant part. With the string hypothesis of Minoru Takahashi, the features of the ground state and low-lying excited states of this model are discussed explicitly by analytical and numerical methods. Especially for a N=2 system, the two bosons being pairs is obvious, and the ground state which is independent of the coupling constant should be ferromagnetic.