Strong decays of the $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 as a $$\varLambda {\bar{K}}$$ Λ K ¯ and $$\varSigma {\bar{K}}$$ Σ K ¯ molecule

Abstract

Abstract In this work, we study the strong decays of the newly observed $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 assuming that it is a meson-baryon molecular state of $$\varLambda {\bar{K}}$$ Λ K ¯ and $$\varSigma {\bar{K}}$$ Σ K ¯ . We consider four possible spin-parity assignments $$J^P=1/2^{\pm }$$ J P = 1 / 2 ± and $$3/2^{\pm }$$ 3 / 2 ± for the $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 , and evaluate its partial decay width into $$\varXi \pi $$ Ξ π and $$\varXi \pi \pi $$ Ξ π π via hadronic loops with the help of effective Lagrangians. In comparison with the Belle data, the calculated decay width favors the spin-party assignment $$1/2^-$$ 1 / 2 - while the other spin-parity assignments do not yield a decay width consistent with data in the molecule picture. We find that about 52–68% of the total width comes from the $${\bar{K}}\varLambda $$ K ¯ Λ channel, while the rest is provided by the $${\bar{K}}\varSigma $$ K ¯ Σ channel. As a result, both channels are important in explaining the strong decay of the $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 . In addition, the transition $$\varXi (1620)^0\rightarrow \pi \varXi $$ Ξ ( 1620 ) 0 → π Ξ is the main decay channel in the $$J^{P}=1/2^{-}$$ J P = 1 / 2 - case, which almost saturates the total width. These information are helpful to further understand the nature of the $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 .