Dirac's method for constraints - an application to quantum wires,the 0.7 conductance anomaly

Abstract

We investigate the Hubbard model in the limit $U=\infty$, which is equivalent to the statistical condition of exclusion of double occupancy. We solve this problem using Dirac's method for constraints. The constraints are solved within the Bosonization method. We find that the constraints modify the anomalous commutator. We apply this theory to quantum wires at finite temperatures where the Hubbard interaction is $U=\infty$. We find that the anomalous commutator induced by the constraints gives rise to the 0.7 anomalous conductance.