One or two poles for the $\Xi(1820)$?

TL;DR

This paper offers a new interpretation of the $ ext{Xi}(1820)$ resonance, suggesting it comprises two states with different widths, explaining recent experimental observations that differ from previous data.

Contribution

It introduces a two-state model for the $ ext{Xi}(1820)$ resonance based on chiral unitary theory, reconciling theoretical predictions with recent experimental results.

Findings

Two $ ext{Xi}(1820)$ states predicted with different widths

The two-state model explains the BESIII measurement

Resolves discrepancy with PDG data

Abstract

In this talk, we present a new interpretation for the recently observed $\Xi(1820)$ resonance. We recall that the chiral unitary approach for the interaction of pseudoscalar mesons with the baryons of the decuplet predicts two states for the $\Xi(1820)$ resonance, one with a narrow width and the other one with a large width. We contrast this fact with the recent BESIII measurement of the $K^- \Lambda$ mass distribution in the $\psi(3686)$ decay to $K^- \Lambda \bar\Xi^+ $, which demands a width much larger than the average of the PDG, and show how the consideration of the two $\Xi(1820)$ states provides a natural explanation to this apparent contradiction.