Energy Spectrum for Neutral Collective Excitations in Striped Hall   States
  Neutral collective excitations in the striped Hall state are studied by using the single mode approximation and Hartree-Fock approximation at the half-filled third and fourth Landau level. We find that the spectrum includes anisotropic NG modes and periodic line nodes. 
N. Maeda, T. Aoyama, Y. Ishizuka and K. Ishikawa