Covariant spectator quark model description of the γ*Λ→Σ0 transition

Abstract

We study the γ*Λ→Σ0 transition form factors by applying the covariant spectator quark model. Using the parametrization for the baryon core wave functions as well as for the pion cloud dressing obtained in a previous work, we calculate the dependence on the momentum transfer squared, Q², of the electromagnetic transition form factors. The magnetic form factor is dominated by the valence quark contributions. The final result for the transition magnetic moment, a combination of the quark core and pion cloud effects, turns out to give a value very close to the data. The pion cloud contribution, although small, pulls the final result towards the experimental value. The final result, μ(sub)ΛΣ0=-1.486μN, is about one and a half standard deviations from the central value in PDG, μ(sub)ΛΣ0=-1.61±0.08μN. Thus, a modest improvement in the statistics of the experiment would permit the confirmation or rejection of the present result. Small but nonzero values for the electric form factor in the finite Q² region are also predicted, as a consequence of the pion cloud dressing.