Radiative decay of the Ξ(1620) in a hadronic molecule picture
Yin Huang (School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, China); Feng Yang (School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, China); HongQiang Zhu (College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, China)
Last year, the $ \Xi(1620) $ state, which is cataloged in the Particle Data Group (PDG) with only one star, was reported again in the $ \Xi(1620) $ final state by the Belle Collaboration. Its properties, such as the spectroscopy and decay width, cannot be simply explained in the context of conventional constituent quark models. This inspires an active discussion on the structure of this resonance. In this paper, we study the radiative decays of the newly observed $ \Xi(1620) $ assuming that it is a meson-baryon molecular state of $ \Xi(1620) $ and $ \Xi(1620) $ with spin-parity $ \Xi(1620) $ developed in our previous study. The partial decay widths of the $ \Xi(1620) $ molecular state into $ \Xi(1620) $ and $ \Xi(1620) $ final states through hadronic loops are evaluated using effective Lagrangians. The partial widths for $ \Xi(1620) $ is evaluated to be approximately $ \Xi(1620) $ keV, which may be accessible for the LHCb experiment. If $ \Xi(1620) $ is a $ \Xi(1620) $ molecule, the radiative transition strength $ \Xi(1620) $ is considerably small and the decay width is of the order of 0.01 eV. Future experimental measurements of these processes can be useful to test the molecule interpretations of the $ \Xi(1620) $ .
