Intrasubband excitations of composite fermions in a quantum wire

We investigate the intrasubband excitation spectra of a composite fermion system in a quantum wire at the filling factor 1/3. Using a second-quantized fermion path-integral approach, we derive the density-density correlation function in the system. We find that at long-wavelength limit the excitation energy of the collective mode has a gap, and that in long-wavelength single-particle excitations are suppressed. We also show that at the finite wave vector the collective mode dispersion has a magnetoroton dip. With increasing the strength of the confining potential, this dip vanishes. © 1996 The American Physical Society.