科研之友
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摘要
In this work, we propose the possible assignment of the newly observed X(2239), as well as η(2225),as a molecular state from the interaction of a baryon Λ and an antibaryon ■.With the help of effective Lagrangians, the Λ■ interaction is described within the one-boson-exchange model with η,η’,ω,?,and σ exchanges considered.After inserting the potential kernel into the quasipotential Bethe-Salpeter equation, the bound states from the Λ■ interaction can be studied by searching for the pole of the scattering amplitude. Two loosely bound states with spin parities IG(JPC)=0+(0-+) and 0-(1--) appear near the threshold with almost the same parameter.The 0-(1--) state canbe assigned to X(2239) observed at BESⅢ, which is very close to the Λ■ threshold. The scalar meson η(2225) can be interpreted as a 0+(0-+) state from the Λ■ interaction. The annihilation effect is also discussed through a coupledchannel calculation plus a phenomenological optical potential. It provides large widths to two bound states produced from the Λ■ interaction. The mass of the 1- state is slightly larger than the mass of the 0- state after including the annihilation effect, which is consistent with our assignment of these two states as X(2239) and η(2225),respectively.The results suggest that further investigation is required to understand the structures near the Λ■ threshold, such as X(2239),η(2225),and X(2175).
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