Speaker
Description
The Λ(1405) hyperon (JP = 1/2−), situated just below the ¯KN threshold, has been a long-standing candidate for an exotic ¯KN molecular structure. Chiral-unitary models propose that it consists of two isospin I = 0 poles with different couplings to the ¯KN and Σ0π0 systems, leading to a line shape that deviates from a relativistic Breit-Wigner distribution. The GlueX experiment at Jefferson Lab provides a unique opportunity to study this phenomenon using the reaction γp → K+Λ(1405), followed by Λ(1405) → Σ0π0 and Λ(1405) → pK−. Utilizing data from the first phase of GlueX, with a photon beam energy range of 6.5–11.6 GeV incident on a liquid hydrogen target, the highest-ever statistics for this state have been achieved.
To benchmark our results, we compare them to the nearby Λ(1520) hyperon
(JP = 3/2−), a conventional quark-model state. Published GlueX results for the pK− decay mode of the Λ(1520) have been refined with additional analyses to extract its total cross-section. A novel approach of joint fits to the mass distributions of both hyperons is employed to disentangle overlapping features, particularly where the Λ(1405) tail contributes under the Λ(1520). This comprehensive study provides new insights into the exotic structure of the Λ(1405) and its implications for hadronic physics.
