Electromagnetic Structure of Light Baryons in Lattice QCD

A method for computing electromagnetic properties of hadrons in lattice QCD is applied to the extraction of electromagnetic properties of the octet baryons. This allows a determination of the full dependence of the baryon masses on the charges and masses of the valence quarks. Results of a first numerical study (at $\beta=5.7$ with Wilson action and light quark masses fixed from the pseudoscalar meson spectrum) are reported. The octet baryon isomultiplet splittings (with statistical errors) are found to be: ${\rm N} - {\rm P} = 1.55(\pm 0.56)$, $\Sigma^0 - \Sigma^+ = 2.47(\pm 0.39)$, $\Sigma^- - \Sigma^0 = 4.63(\pm 0.36)$ and $\Xi^- - \Xi^0 = 5.68(\pm 0.24)$ MeV. Estimates of the systematic corrections arising from finite volume and the quenched approximation are included in these results.