Bulk tunneling at integer quantum Hall transitions

The tunneling into the bulk of a 2D electron system in a strong magnetic fi eld is studied near integer quantum Hall transitions. We present a nonpertu rbative calculation of the tunneling density of states (TDOS) for both Coul omb and short-ranged electron-electron interactions. In the case of the Cou lomb interaction, the TDOS exhibits a 2D quantum Coulomb gap behavior, v(ep silon) = C-Q\epsilon\/e(4), where C-Q is a nonuniversal coefficient of quan tum mechanical origin. For short-ranged interactions, we find that the TDOS at low bias follows v(epsilon)/v(0) = 1 + (\epsilon\/epsilon(0))(gamma), w here gamma is a universal exponent determined by the scaling dimension of s hort-ranged interactions.