Baryon current matrix elements in a light-front framework.

Abstract

Current matrix elements and observables for electro- and photo-excitation of baryons from the nucleon are studied in a light-front framework. Relativistic effects are estimated by comparison to a nonrelativistic model, where we use simple basis states to represent the baryon wave functions. Sizeable relativistic effects are found for certain transitions, for example, to radial excitations such as that conventionally used to describe the Roper resonance. A systematic study shows that the violation of rotational covariance of the baryon transition matrix elements stemming from the use of one-body currents is generally small.