Electromagnetic and spin polarizabilities in lattice QCD

We discuss the extraction of the electromagnetic and spin polarizabilities of nucleons from lattice QCD. We show that the external field method can be used to measure all the electromagnetic and spin polarizabilities including those of charged particles. We then turn to the extrapolations required to connect such calculations to experiment in the context of finite volume chiral perturbation theory. We derive results relevant for lattice simulations of QCD, partially-quenched QCD and quenched QCD. Our results for the polarizabilities show a strong dependence on the lattice volume and quark masses, typically differing from the infinite volume limit by similar to 10% for current lattice volumes and quark masses.