Based on the color-spin interaction in diquarks, we argue why some multiquark configurations could be stable against strong decay when heavy quarks are included. After showing the stability of previously discussed states we identify new possible stable states. These are the $T^0_{cb}(ud \bar{c}\bar{b})$ tetraquark, the $Θ_{bs}(udus \bar{b})$ pentaquark and the $H_c(udusuc)$ dibaryon, and so forth.
This work is a continuation in our series of papers, that addresses quark models of hadronic structure on the light front, motivated by the QCD vacuum structure and lattice results. In this paper we focus on the importance of diquark correlations, which we describe by a quasi-local four-fermion effective 't Hooft interaction induced by instantons. The same interaction is also shown to generate extra quark-antiquark pair of the "sea". Its higher order iteration can be included via "pion-mediation": both taken together yield a quantitative description of the observed flavor asymmetry of antiquar…
A review is presented of some discussions about the fully-heavy tetraquarks made of two charmed quarks and two anticharmed antiquarks, and other multiquark states involving some heavy flavors.
最近报道的2.32 GeV/c的奇异共振表明可能存在多夸克态。本文综述了三种多夸克束缚态。以前的模型无关变分方法认为一个四夸克与两个重反夸克和两个轻夸克作为一个重反双夸克与色场的夸克绑定到两个轻夸克与一个波函数像一个重子。结果表明，与“分子型”$D-K$和$B-K$波函数不同，具有这种“双夸克重子”波函数的粲奇四夸克$\bar c \bar s u d$或底奇四夸克$\bar b \bar s u d$是不受束缚的.然而，一个粲底四夸克$\bar c \bar b u d$可能与一个非常窄的弱衰变模结合。“分子型”$D-B$态可以具有有趣的具有高能量π介子的$B_c π$衰变，
We construct the diquark-diquark-diquark type vector six-quark currents to investigate the vector and scalar hexaquark states in the framework of the QCD sum rules in a consistent way, and make predictions for the hexaquark masses. We can search for the fully-heavy hexaquark states in the di-$ Ω_{ccc}$ and di-$ Ω_{bbb}$ invariant mass spectra in the future. Combined with our previous works on the fully-heavy tetraquark states and pentaquark states, the present predictions can shed light on the nature of the fully-heavy multiquark states.
We discuss whether the bound nature of multiquark states in quark models could benefit from relativistic effects on the kinetic energy operator. For mesons and baryons, relativistic corrections to the kinetic energy lead to lower energies, and thus call for a retuning of the parameters of the model. For multiquark states, as well as their respective thresholds, a comparison is made of the results obtained with non-relativistic and relativistic kinetic energy. It is found that the binding energy is lower in the relativistic case. In particular, $QQ\bar q\bar q$ tetraquarks with double heavy fla…
The existence of stable multiquarks made of heavy quarks and antiquarks is discussed in the framework of potential models. It is stressed that the few-body problem should be handled seriously and accurately. No bound state is found within the current models. But resonances are likely present in the spectrum above the lowest threshold.
Motivated by the discovery of fully open-flavor tetraquark states $X_0(2900)$ and $X_1(2900)$ by the LHCb Collaboration, the magnetic dipole moment of the $X_1(2900)$ state with the quantum numbers $ J^{P} = 1^{-}$ is determined in the diquark-antidiquark picture using the light-cone sum rules. The numerical result is obtained as $ μ_{X_1}=0.79^{+0.36}_{-0.39}\,μ_N$. The magnetic moments of hadrons encompasses useful knowledge on the distributions of charge and magnetization their inside, which can be used to better understand their geometrical shapes and quark-gluon organizations. The observa…
In recent years there has been a rapidly growing body of experimental evidence for existence of exotic, multiquark hadrons, i.e. mesons which contain additional quarks, beyond the usual quark-antiquark pair and baryons which consist of more than three quarks. In all cases with robust evidence they contain at least one heavy quark Q=c or b, the majority including two heavy quarks. Two key theoretical questions have been triggered by these discoveries: (a) how are quarks organized inside these multiquark states -- as compact objects with all quarks within one confinement volume, interacting via …
Probing the electromagnetic structure of the $P_c(4337)^+$ pentaquark: Insights from a diquark-diquark-antiquark picture for $J^P = \frac{1}{2}^-$ and $\frac{3}{2}^-$ states
