UC Berkeley

Meson-baryon systems with strangeness content provide a unique laboratory for investigating the strong interaction and testing theoretical models of hadron structure and dynamics. In this work, the measured correlation functions for oppositely charged Ξ-K and Ξ − π pairs obtained in high-multiplicity pp collisions at s = 13 TeV at the LHC are presented. For the first time, high-precision data on the Ξ-K interaction are delivered at small relative momenta. The scattering lengths, extracted via the Lednický–Lyuboshits expression of the pair wavefunction, indicate a repulsive and a shallow attractive strong interaction for the Ξ-K and Ξ − π systems, respectively. The Ξ(1620) and Ξ(1690) states are observed in the Ξ − π correlation function and their properties, mass and width, are determined. These measurements are in agreement with other available results. Such high-precision data can help refine the understanding of these resonant states, provide stronger constraints for chirally motivated potentials, and address the key challenge of describing the coupled-channel dynamics that may give rise to molecular configurations.