Tunneling in a bosonized Fermi liquid

We apply the bosonization technique to the problem of tunneling in a Fermi liquid, and present a semiclassical theory of tunneling rates. To test the method, we derive and evaluate an expression for the tunneling current in the problem of two parallel Luttinger liquids. Next we study tunneling between parallel two dimensional Fermi liquids. In the absence of a magnetic field, the conductance $I/V$ has a resonance peak at zero bias. Our estimate for the peak broadening agrees with the many-body theory results. In a magnetic field perpendicular to the plane, we find a tunneling gap linear in the field, in agreement with the experiment. In this regime the tunneling is spatially coherent over a distance of the order of the cyclotron radius. The coherence can be probed by a magnetic field parallel to the plane, which gives an Aharonov-Bohm phase to the tunneling amplitude. As a result, the current is an oscillatory function of the field.