Hall Coefficient for the Two-Dimensional Hubbard Model

We calculate with quantum Monte Carlo methods the Hall coefficient $R_H$ for the 2D Hubbard model at small hole doping near half filling. In the weak coupling regime $R_H$ is electronlike. In the strong coupling regime, where the mapping to the $t$- $J$ model is justified, $R_H$ is electronlike with small amplitude in the temperature regime $T>U$, $T<J$ and holelike in the temperature regime $J<T<U$. Our results are consistent with the picture of a Mott transition driven by the divergence of the effective mass as opposed to the vanishing of the number of charge carriers.