Dimer-dimer zero crossing and dilute dimerized liquid in a one-dimensional mixture

We consider the system of dimers formed in a one-dimensional mass-balanced Bose-Bose mixture of species σ=↑,↓ with attractive interspecies and repulsive intraspecies contact interactions. In the plane parametrized by the ratios of the coupling constants g↑↑/|g↑↓| and g↓↓/|g↑↓| we trace out the curve where the dimer-dimer interaction switches from attractive to repulsive. We find this curve to be significantly (by more than a factor of 2) shifted towards larger gσσ (or smaller |g↑↓|) compared to the mean-field stability boundary g↑↑g↓↓=g↑↓2. For a weak dimer-dimer attraction we predict a dilute dimerized liquid phase stabilized against collapse by a repulsive three-dimer force. © 2018 American Physical Society.