Negative magnetoresistance of the normal state of the doped Mott insulator

We show that the gauge theory of the two-dimensional doped Mott insulator predicts an anomalous anisotropic negative contribution to the magnetoresistance, which dominates at low temperatures. This anomalous contribution to the magnetoresistivity falls rapidly with increasing temperature, so the total magnetoresistivity is positive at room temperatures. This effect is due to orbital motion and is highly anistropic with respect to the orientation of the magnetic field. We discuss possible applications of these results to the high-${\mathit{T}}_{\mathit{c}}$ materials.