Composite-Fermion Analysis of the Double-Layer Fractional Quantum Hall System

Effect of interlayer tunneling in the double-layer fractional quantum Hall system at the total Landau level filling of $\nu=1/m$ ($m$: odd integer) is analyzed with the composite-fermion approach in which the flux attachment is directly applied to the electron-electron interaction. A comparison with a numerical result indicates that the vertically coupled Laughlin liquids may be regarded as a system of composite fermions with {\em reduced} interparticle interactions and {\em unchanged} interlayer tunneling, which makes the quantum-Hall regime, identified by a gap in the pseudospin-wave excitation mode, wider as $\nu$ becomes $1/3,1/5,\ldots$.