Valence quark and meson cloud contributions for the γ*Λ→Λ* and γ*Σ⁰→Λ* reactions

Abstract

We estimate the valence quark contributions for the γ*Y→Λ* (Y=Λ, Σ0) electromagnetic transition form factors. We focus particularly on the case of Λ*=Λ(1670) as an analogue reaction with γ*N→N(1535). The results are compared with those obtained from chiral unitary model, where the Λ* resonance is dynamically generated and thus the electromagnetic structure comes directly from the meson cloud excitation of the baryon ground states. The form factors for the case Y=Σ0 in particular, depend crucially on the two real phase (sign) combination, a phase between the Λ and Λ* states, and the other, the phase between the Λ and Σ0 radial wave functions. Depending on the combination of these two phases, the form factors for the γ*Σ0→Λ* reaction can be enhanced or suppressed. Therefore, there is a possibility to determine the phase combination by experiments.