Is JPC=3-+ molecule possible?

The confirmation of charged charmonium-like states indicates that heavy quark molecules should exist.Here we discuss the possibility of a molecule state with J P C= 3-+. In a one-boson-exchange model investigation for the S wave C = + D* ˉD*2states, one finds that the strongest attraction is in the case J = 3 and I = 0 for bothπ and σ exchanges. Numerical analysis indicates that this hadronic bound state might exist if a phenomenological cutoff parameter around 2.3 Ge V(1.5 Ge V) is reasonable with a dipole(monopole) type form factor in the one-pionexchange model. The cutoff for binding solutions may be reduced to a smaller value once the σ exchange contribution is included. If a state around the D* ˉD*2threshold(≈4472 Me V) in the channel J/ψω(P wave) is observed, the heavy quark spin symmetry implies that it is not a cˉc meson and the J P C are likely to be 3-+.     

神奇有趣的五夸克态

对今年国际上有关五夸克态的实验与理论研究现状作一个总体的评述 ,指出了有待解决的主要问题和相关的一些背景知识 ,并简单介绍了作者所在研究小组的有关研究工作 .     

Double-heavy tetraquark states with heavy diquark-antiquark symmetry

We calculate the masses of the QQqq(Q=c,b:q=u,d,s)tetraquark states with the aid of heavy diquark-antiquark symmetry(HDAS)and the chromomagnetic interaction(CMI)model.The masses of the highestspin(J=2)tetraquarks that have only the(QQ)(3):(qq)₃.color structure are related with those of conventional hadrons using HDAS.Thereafter,the masses of their partner states are determined with the mass splittings in the CMI model.Our numerical results reveal that(i)the lightest ccnn(n=u,d)is an I(J^P)=0(1⁺)state around 3929 MeV(53 MeV above the DD^* threshold),and none of the double-charm tetraquarks are stable;(ii)the stable double-bottom tetraquarks are the lowest 0(1⁺)bbin around 10488 MeV(≈116 MeV below the BB^*threshold)and the lowest 1/2(1⁺)bbns around 10671 MeV(≈20 MeV below the BB_s^*/B_sB^*threshold);and(iii)the two lowest bcnn tetraquarks,namely the lowest 0(0⁺)around 7167 MeV and the lowest 0(1)around 7223 MeV,are in the nearthreshold states.Moreover,we discuss the constraints on the masses of double-heavy hadrons.Specifically,for the lowest nonstrange tetraquarks,we obtain T_cc<3965 MeV,T_bb<10627 MeV,and T_bc<7199 MeV.     

Jaffe与Wilczek双夸克模型中的负宇称五夸克态

如果Jaffe与Wilczek关于Q5+五夸克态的双夸克图像是正确的话,那就应该存在负宇称的五夸克SU(3)八重态与单态,其中两个双夸克间没有轨道激发.这些态比Q5+质量低,与传统夸克模型中的由三夸克构成的重子的轨道激发质量接近.我们计算了这些负宇称态的质量与磁矩,用手征有效拉氏量讨论了他们可能的强衰变模式和选择定择，发现有两个态可能比较窄.我们建议实验上寻找这九个额外的负宇称态.如果将来的实验确实发现了这些态,那是对Jaffe与Wilczek双夸克模型的直接验证.否则,应该重新评估Jaffe与Wilczek的双夸克图像甚至抛弃这个模型.     

宇称为正角动量为3/2的五夸克态的磁矩

如果将来的实验证实五夸克态Θ+ 5与Ξ- - 5的JP=12+ ,在一些理论模型中,JP=32+ 与JP=12+ 的五夸克态必然同时出现.这些态有可能很快会发现.我们在不同理论模型中计算了JP=32+ 的五夸克态的磁矩.     

Δ contribution to the parity-violating nucleon-nucleon force

Because the nucleon may be excited and transformed into a virtual Δ resonance easily, we consider the decuplet contribution to the parity-violating (PV) nucleon-nucleon interaction in the chiral effective field theory. The effective PV nucleon-nucleon potential is derived without introducing any unknown coupling constants.     

Hidden-charm Pentaquark Production at e~+e~- Colliders

We study one possible production mechanism for the hidden-charm pentaquark via a color-octet cc pair fragmentation in e~+e~-collision.The pentaquark production at B factory energy is dominated by e~+e~-→ccg→P_c+X,while at Z~0pole energy,there are several partonic processes playing significant role.Our results show that it is possible to search for the direct pentaquark production signal at e~+e~-colliders,which is important to understand the properties of pentaquark.