Electromagnetic response and effective gauge theory of double-layer   quantum Hall systems
  We report on an effective gauge theory of double-layer quantum Hall systems, that is constructed via bosonization from the response of incompressible states without referring to composite bosons and fermions. It is pointed out that dipole-active excitations, both elementary and collective, govern the long-wavelength features of quantum Hall systems, and the single-mode approximation is used to study them. The effective theory consists of three vector fields representing one interlayer collective mode and two cyclotron modes, and properly incorporates the spectrum of collective excitations on the right scale of the Coulomb interaction. Special emphasis is placed on exploring the advantage of looking into quantum Hall systems through their response; in particular, subtleties inherent to the standard Chern-Simons theories are critically examined. 
K. Shizuya