What is the role of the meson cloud in the $\Sigma^{*0} \to \gamma \Lambda$ and $\Sigma^\ast \to \gamma \Sigma$ decays?

Abstract

We study the effect of the meson cloud dressing in the octet baryon to decuplet baryon electromagnetic transitions. Combining the valence quark contributions from the covariant spectator quark model with those of the meson cloud estimated based on the flavor SU(3) cloudy bag model, we calculate the transition magnetic form factors at $Q^2=0$ ($Q^2=-q^2$ and $q$ the four-momentum transfer), and also the decuplet baryon electromagnetic decay widths. The result for the $\gamma^\ast \Lambda \to \Sigma^{\ast 0}$ decay width is in complete agreement with the data, while that for the $\gamma^\ast \Sigma^+ \to \Sigma^{\ast +}$ is underestimated the data by 1.4 standard deviations. This achievement may be regarded as a significant advance in the present theoretical situation.