The electromagnetic Sigma-to-Lambda transition form factors with coupled-channel effects in the space-like region

Abstract

Using dispersion theory, the electromagnetic Sigma-to-Lambda transition form factors are expressed as the product of the pion electromagnetic form factor and the ππ → ΣΛ scattering amplitudes with the latter estimated from SU(3) chiral perturbation theory including the baryon decuplet as explicit degrees of freedom. The contribution of the K K channel is also taken into account and the ππ-K K coupledchannel effect is included by means of a two-channel Muskhelishvili-Omnès representation. It is found that the electric transition form factor shows a significant shift after the inclusion of K K channel, while the magnetic transition form factor is only weakly affected. The error bands of the Sigma-to-Lambda transition form factors from the uncertainties of the couplings in three-flavor chiral perturbation are estimated by a bootstrap sampling method.