Hall Coefficient for the Two-Dimensional Hubbard Model

We calculate with quantum Monte Carlo methods the Hall coefficient RH for the 2D Hubbard model at small hole doping near half filling. In the weak coupling regime RH is electronlike. In the strong coupling regime, where the mapping to the t- J model is justified, RH 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.