Strange molecular partners of the and
Zhi Yang (School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, China); Xu Cao (University of Chinese Academy of Sciences, Beijing 100049, China, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China); Feng-Kun Guo (University of Chinese Academy of Sciences, Beijing 100049, China, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China); Juan Nieves (Instituto de Física Corpuscular (centro mixto CSIC-UV), Institutos de Investigación de Paterna, Apartado 22085, 46071, Valencia, Spain); Manuel Pavon Valderrama (School of Physics, International Research Center for Nuclei and Particles in the Cosmos and Beijing Key Laboratory of Advanced Nuclear Materials and Physics, Beihang University, Beijing 100191, China)
Quantum chromodynamics presents a series of exact and approximate symmetries which can be exploited to predict new hadrons from previously known ones. The and , which have been theorized to be isovector and molecules [], are no exception. Here we argue that from SU(3)-flavor symmetry, we should expect the existence of strange partners of the ’s with hadronic molecular configurations and (or, equivalently, quark content , with , ). The quantum numbers of these and structures would be . The predicted masses of these partners depend on the details of the theoretical scheme used, but they should be around the and thresholds, respectively. Moreover, any of these states could be either a virtual pole or a resonance. We show that, together with a possible triangle singularity contribution, such a picture nicely agrees with the very recent BESIII data of the .