Disconnection Transition in an Extended Delta-Function Bose Gas

Abstract

A disconnection transition is aphase transition which accompanies a change in the connectedness ofthe fermi sea. The existence of such a transition is established in thecontext of a one-dimensional interacting model. The model considered is an extension of the deltafunction bose gas in which its fourth order conservation law is addedto the original hamiltonian. For low density, the ground state of themodel consists of two separated fermi seas and there are two distinctbranches of excitations. At a critical density, one branch ofexcitations disappears, and there is a second order phase transition toa single fermi sea ground state.