Isospin and a possible interpretation of the newly observed X(1576)

Abstract

Recently, the BES collaboration observed a broad resonant structure X(1576) with a large width being around 800 MeV and assigned its $J^{PC}$ number to $1^{--}$. We show that the isospin of this resonant structure should be assigned to 1. This state might be a molecule state or a tetraquark state. We study the consequences of a possible $K^{\ast }(892)$-$\bar{\kappa }$ molecular interpretation. In this scenario, the broad width can easily be understood. By using the data of $B(J/\psi \to X{\pi }^0)\cdot B(X\to K^{+}{K}^{-})$, the branching ratios $B(J/\psi \to X{\pi }^0)\cdot B(X\to {\pi }^{+}{\pi }^{-})$ and $B(J/\psi \to X{\pi }^0)\cdot B(X\to K^{+}{K}^{-}{\pi }^{+}{\pi }^{-})$ are further estimated in this molecular state scenario. It is shown that the $X\to {\pi }^{+}{\pi }^{-}$ decay mode should have a much larger branching ratio than the $X\to K^{+}{K}^{-}$ decay mode has. As a consequence, this resonant structure should also be seen in the $J/\psi \to {\pi }^{+}{\pi }^{-}{\pi }^0$ and $J/\psi \to K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}{\pi }^0$ processes, especially in the former process. Carefully searching this resonant structure in the $J/\psi \to {\pi }^{+}{\pi }^{-}{\pi }^0$ and $J/\psi \to K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}{\pi }^0$ decays should be important for understanding the structure of X(1567).

Comments: 5 pages, ReVTeX4, 3 figures. Version accepted for publication as a brief report in Phys. Rev. D