分类： 物理学 >> 核物理学 提交时间： 2016-09-14
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.
分类： 物理学 >> 核物理学 提交时间： 2016-09-14
摘要： We establish the factorization formula for scalar Glueball production through radiative decays of vector states of heavy quarkonia, e.g. J/ψ, ψ(2S) and Υ(nS), where the Glueball mass is much less than the parent heavy quarkonium mass. The factorization is demonstrated explicitly at one-loop level through the next-to-leading order (NLO) corrections to the hard kernel, the non-relativistic QCD (NRQCD) long-distance matrix element (LDMEs) of the heavy quarkonium, and the light-cone distribution amplitude (LCDA) of scalar Glueball. The factorization provides a comprehensive theoretical approach to investigate Glueball production in the radiative decays of vector states of heavy quarkonia and to determine the physic nature of Glueball. We discuss the scale evolution equation of LCDA for scalar Glueball. In the end, we extract the value of the decay constant of Scalar Glueball from Lattice QCD calculation and analyze the mixing effect among f0(1370), f0(1500) and f0(1710).
分类： 物理学 >> 核物理学 提交时间： 2016-09-14
摘要： In this paper, we study double charmonia production in Upsilon peaks, especially, a S-wave charmonium ηc and a P-wave charmonium hc(1P1), or a S-wave charmonium J/ψ and the X(3940) and X(4160) within the nonrelativistic QCD (NRQCD) approach which is a powerful tool to realize the factorization of double charmonia production in electron-positron annihilation. The JPC=1−− state Υ(nS) can provide an ideal laboratory for studying the properties of double-heavy quarkonium and also can separate the perturbative and nonperturbative parts due to the large heavy quark mass compared with the typical hadron scale ΛQCD. Explanation of the X(3940) and X(4160) as the 31S0 and 41S0 states, respectively, are compatible with the observed upper limits for the branching fractions of Υ(1S,2S)→J/ψ+X, where X=X(3940), X(4160) by the Belle Collaboration. The branching fractions of Υ(1S,2S,3S)→ηc+hc(1P1) are predicted to be around 10−6, which shall be tested in Belle-II experiments.
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