Semi-invisible Hyperon Decays in the Effective Lagrangian Approach

Abstract

We systematically investigate the semi-invisible decays of hyperons (hyperon $\to \pi(/\gamma)\ +$ invisible($\psi$)) in the Mesogenesis mechanism by the effective Lagrangian approach. The one-loop hadronic contribution of triangle diagrams with final-state interactions is fully examined in the present work. Our analysis indicates that the triangle diagram yield sizable corrections to the branching ratio that are as significant as those from tree diagrams. Especially for the $\Sigma^-\to \pi^-\psi$ and $\Xi^0 \to \pi^0 \psi$, their loop contributions cannot be ignored. Consequently, the branching ratios of hyperon hadronic semi-invisible decays are found to be of order $10^{-5}$, particularly for $\Sigma^+\to\pi^+\psi$, $\Xi^0\to\pi^0\psi$, and $\Xi^-\to\pi^-\psi$, whereas those of radiative semi-invisible decays are less than $10^{-7}$.