Radiative decays of the $Λ(1520)$ as a dynamically generated resonance

Abstract

Inspired by the latest BESIII measurement of the $Λ(1520)\toγΣ^0$ radiative decay, we systematically study the decays $Λ(1520)\toγΛ(Σ^0)$ within the chiral unitary approach, where the $Λ(1520)$ is treated as a dynamically generated resonance from meson-baryon interactions. Compared with previous chiral unitary studies, we adopt dimensional regularization for $S$-wave loop integrals to preserve gauge invariance and, for the first time, include Feynman diagrams with photon coupling to intermediate baryons. Our calculated partial decay width $Γ(Λ(1520)\toγΣ^0)$ agrees well with the new BESIII data, whereas the predicted $Γ(Λ(1520)\toγΛ)$ is considerably smaller than the CLAS experimental result. By comparing our results with predictions from various quark models, we discuss the internal nature of the $Λ(1520)$ resonance, highlight its complex component structure, and stress the need for more refined theoretical frameworks and further experimental measurements.