Electromagnetic moments of quasi‐stable baryons
We address electromagnetic properties of quasi‐stable baryons in the context of chiral extrapolations of lattice QCD results. For particles near their decay threshold we show that an application of a small external magnetic field changes the particle’s energy in a non‐analytic way. The conventional electromagnetic moments are only well‐defined when the background field B satisfies |eB|/2M*≪|M*−M−m| where M* is the mass of the resonance and M, m the masses of the decay products. A direct application of this situation is the chiral extrapolation of the Δ(1232)‐isobar electromagnetic properties. We discuss such an extrapolation of the Δ(1232)‐isobar magnetic dipole, electric quadrupole and magnetic octupole moments by a covariant chiral effective field theory.