  Hall coefficient implies the mechanism for reconstruction of a Fermi surface,
distinguishing competing scenarios for Mott criticality such as electron
fractionalization, dynamical mean-field theory, and metal-insulator transition
driven by symmetry breaking. We find that electron fractionalization leaves a
signature for the Hall coefficient at Mott criticality in two dimensions, a
unique feature differentiated from other theories. We evaluate the Hall
coefficient based on the quantum Boltzman equation approach, guaranteeing gauge
invariance in both longitudinal and transverse transport coefficients.
