Quark masses using domain wall fermions

Due to the attractive features that domain wall fermions possess with respect to chiral symmetry, we continue our investigation of the light quark masses with this discretization. Achieving reliable results, especially for $(m_u + m_d)/2$, requires strict control of systematic uncertainties. Our present results were obtained on a quenched $\beta =6.0$ lattice with spatial volume $\approx (1.5~{\rm fm})^3$. Consequently we remark on effects of finite volume as well as finite extent in the fictitious fifth dimension. We compute the renormalization factors nonperturbatively and compare to the one--loop perturbative result.