Recent investigations into the doubly strange baryons Ξ(1620) and Ξ(1690) have unveiled properties that pose significant challenges for current theoretical models. These baryons, which are excited states of the Ξ baryon, have been the subject of a considerable volume of experimental data from various collaborations in recent years. The new data have motivated a detailed analysis of meson-baryon interactions using a coupled-channel approach, aiming to reconcile observations with theoretical predictions based on chiral and hidden local symmetries.

The study focused on systems composed of pseudoscalar and vector mesons, considering a configuration with total spin 1/2 and isospin 1/2. Researchers attempted to describe two key sets of experimental data: first, the K-Λ femtoscopic correlation function obtained from proton-proton and lead-lead collisions; second, the invariant mass distributions for various meson-baryon systems, including πΞ, K̄Σ, and K̄Λ. The methodology employed tree-level interactions derived from Lagrangians based on chiral and hidden local symmetries.

The research findings have highlighted a fundamental discrepancy. It was found that the theoretical amplitude that successfully describes the K-Λ femtoscopic correlation function is inconsistent with the invariant mass distributions of the other meson-baryon systems. Conversely, an amplitude that agrees with the invariant mass distributions fails to reproduce the correlation function. This inconsistency suggests that current models of meson-baryon interactions may not fully capture the complexity of these doubly strange baryons, or that a revision of the underlying interaction parameters or structure is required.