Pentaquark states in a diquark–triquark model

分类： 物理学 >> 核物理学 提交时间： 2016-09-14

Ruilin Zhu Cong-Feng Qiao(2 3)

摘要： The diquark-triquark model is used to explain charmonium-pentaquark states, i.e., Pc(4380) and Pc(4450), which were observed recently by the LHCb collaboration. For the first time, we investigate the properties of the color attractive configuration of a triquark and we define a nonlocal light cone distribution amplitude for pentaquark states, where both diquark and triquark are not pointlike, but they have nonzero size. We establish an effective diquark-triquark Hamiltonian based on spin-orbital interaction. According to the Hamiltonian, we show that the minimum mass splitting between 52+ and 32− is around 100~MeV, which may naturally solve the challenging problem of small mass splitting between Pc(4450) and Pc(4380). This helps to understand the peculiarities of Pc(4380) with a broad decay width whereas Pc(4450) has a narrow decay width. Based on the diquark-triquark model, we predict more pentaquark states, which will hopefully be measured in future experiments.

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