SHOT-NOISE IN THE HALF-FILLED LANDAU-LEVEL

Shot noise in the half-filled Landau level is studied within the compo site-fermion picture, focusing on the diffusive regime. The composite fermions are assumed to form a Fermi liquid with nontrivial Fermi-liqu id parameters. The Boltzmann-Langevin equation for this system is deri ved, taking proper account of fluctuations in both the Chern-Simons an d the physical electric and magnetic fields. To leading order in max{e V, T}/E-F, the noise properties of composite fermions are found to equ al those of semiclassical electrons in the external magnetic field. No nequilibrium fluctuations in the Hall voltage are dominated by fluctua tions in the Chern-Simons electric field, reflecting the finite Hall r esistance of the system. The low-frequency noise power is derived in d etail for the Corbino-disk geometry and turns out to be unaffected bot h by nontrivial Fermi-liquid parameters and by the magnetic field. The formalism is also applied to compute thermal density-density and curr ent-current correlators at finite frequency and wave vector.