Equation of state for the one-dimensional attractive \delta-potential   Bose gas in the weak-coupling regime
  Approximated formulae for real quasi-momentum and the associated energy spectrum are presented for one-dimensional Bose gas with weak attractive contact interactions. On the basis of the energy spectrum, we obtain the equation of state in the high temperature region, which is found to be the van der Waals equation without volume correction. 
Tsubasa Ichikawa, Izumi Tsutsui, and Nobuhiro Yonezawa
cond-mat.quant-gas math-ph math.MP quant-ph