Baryons Electromagnetic Mass Splittings in Potential Models

We study electromagnetic mass splittings of charmed baryons. We point out discrepancies among theoretical predictions in non-relativistic potential models; none of these predictions seems supported by experimental data. A new calculation is presented. Quite a successful phenomenology has been obtained using non-relativistic potential models built in order to describe the low-energy limit of QCD. Among the various observables studied in such models, a large amount of work was devoted to the electromagnetic mass differences [1]. In general a good agreement was obtained for nucleon, Σ and Ξ baryons and predictions for charmed baryons were supplied (see table 1). Albeit the predictions for charmed baryons were quite dispersed, some general feature was anyway common to most of the models, as Σ c − Σ c ∼ < Σ c − Σ c . Surprisingly enough, when data about charmed baryons finally appear, none of these models came out in agreement with them. Because of the poor amount of experimental data and large errors, we cannot really exclude that future experimental determination could change the situation. However, aimed by this failure, we have decided to investigate isospinviolating mass differences of baryons in a successful potential model, including all possible contributions. We wish to understand whether the failure of potential models arises from technical problems (as having neglected some contributions, or having used perturbative procedures unproperly, etc.) or reveals some intrinsic limitation of this approach. 1 Supported by the EU Program ERBFMBICT 950427