Critical properties of 1D spin-gapped fermions at the onset of   magnetization
  We develop an effective field theory for finding critical properties of 1D spin gapped fermions at the onset of magnetization. It is shown how the spin-charge interaction leads to a linear critical behavior and finite susceptibility for a wide range of models. We also discuss possible manifestations of spin-charge coupling in cold atomic gases. 
T. Vekua, S.I. Matveenko, and G.V. Shlyapnikov