ELECTRONIC SPECTRAL-FUNCTION FOR A 2-DIMENSIONAL ELECTRON-SYSTEM IN THE FRACTIONAL QUANTUM HALL REGIME

A two-dimensional system of interacting electrons is considered in a s trong magnetic field in the fractional quantum Hall regime, where the motion of the electrons is restricted to the lowest Landau level in th e lowest subband. Starting from a microscopic quantum-field theory we present a calculation of the electronic spectral function A(epsilon) f or a Single layer. From the original Coulomb interaction we separate a n effective bosonic paa, which is treated exactly by resummation of Fe ynman diagrams. For the electron Green's function G(tau-tau'), which i s closely related to A(epsilon), we derive an approximate formula that goes beyond perturbation theory and is similar to the solution of an independent-boson model. The independent bosons are the collective exc itations, mainly magnetorotons. Constructing a bosonic spectral functi on with the main features of the collective excitations by the single- mode approximation, we obtain a spectral function A(epsilon) with a do uble-peak structure and a pseudogap at epsilon approximate to mu for l ow temperatures. From this result we derive the current-voltage charac teristic I(V) for the tunneling of electrons between two layers, which shows a tunneling pseudogap for low temperatures and agrees with rece nt experiments.