Properties of Fluctuations in Two Coupled Chains of Luttinger Liquids
  Two chains of Luttinger liquids coupled by both interchain hopping and interchain interaction are investigated. A degeneracy of two kinds of dominant states with in phase and out of phase ordering in the absence of the hopping is removed since the transverse fluctuation of charge density is completely gapful and that of spin density has two kinds of excitation with and without gap. The crucial effect of the interchain hopping on the electronic properties is studied by calculating susceptibilities. 
Hideo Yoshioka and Yoshikazu Suzumura