# One-dimensional two-component fermions with contact even-wave repulsion and SU(2) breaking near-resonant odd-wave attraction

## TL;DR

This paper investigates a 1D two-component Fermi gas with contact interactions, revealing a first-order phase transition induced by SU(2) symmetry breaking near a resonant odd-wave attraction, affecting the system's spin configuration.

## Contribution

It introduces an effective field theory for the spin degrees of freedom in a 1D Fermi gas with SU(2) symmetry breaking near-resonant odd-wave interactions, identifying a first-order phase transition.

## Key findings

- Identifies a critical odd-wave interaction strength causing a phase transition.
- Shows transition from zero spin phase to spin-segregated phase.
- Derives an effective field theory using bosonization techniques.

## Abstract

We consider a one-dimensional (1D) two-component atomic Fermi gas with contact interaction in the even-wave channel (Yang-Gaudin model) and study the effect of an SU(2) symmetry breaking near-resonant odd-wave interaction within one of the components. Starting from the microscopic Hamiltonian, we derive an effective field theory for the spin degrees of freedom using the bosonization technique. It is shown that at a critical value of the odd-wave interaction there is a first-order phase transition from a phase with zero total spin and zero magnetization to the spin-segregated phase where the magnetization locally differs from zero.