最近，在LHCb中观察到一种新的强子态，质量为6.9 GeV，主要衰变为一对charmonia。数据还揭示了一个更广泛的结构，中心约为6490 MeV，并提出了另一个未经证实的共振中心约为7240 MeV，非常接近两个双重魅力$Ξ_{cc}$重子的阈值。我们认为这些奇异的强子是真正的四夸克，而不是charmonia分子。证明它们是V重子四夸克态，即重子顶点与$cc$双夸克态相连，重子顶点与反重子顶点通过弦相连，反重子顶点与$\bar c \bar c$反双夸克态相连。我们将这些态作为粲偶素类四夸克态$Ψ(4360)$和$Y(4630)$ / $Ψ(4660)$的类似物来研究。检验这些说法的一种方法是寻找在7.2 GeV处的状态显著衰变为$Ξ_{cc}\overlineΞ_{cc}$。这种衰减将是状态$Y(4630)$衰减到$Λ_c\overlineΛ_c$的模拟。我们进一步认为，应该有轨道和径向的$X(6900)$的激发态的轨迹。我们预测它们的质量。其中一些状态可能已经被LHCb看到了。
英文摘要：
Recently a novel hadronic state of mass 6.9 GeV, that decays mainly to a pair of charmonia, was observed in LHCb. The data also reveals a broader structure centered around 6490 MeV and suggests another unconfirmed resonance centered at around 7240 MeV, very near to the threshold of two doubly charmed $Ξ_{cc}$ baryons. We argue in this note that these exotic hadrons are genuine tetraquarks and not molecules of charmonia. It is conjectured that they are V-baryonium tetraquarks, namely, have an inner structure of a baryonic vertex with a $cc$ diquark attached to it, which is connected by a string to an anti-baryonic vertex with a $\bar c \bar c$ anti-diquark. We examine these states as the analogs of the states $Ψ(4360)$ and $Y(4630)$/$Ψ(4660)$ which are charmonium-like tetraquarks. One way to test these claims is by searching for a significant decay of the state at 7.2 GeV into $Ξ_{cc}\overlineΞ_{cc}$. Such a decay would be the analog of the decay of the state $Y(4630)$ into to $Λ_c\overlineΛ_c$. We further argue that there should be trajectories of both orbital and radial excited states of the $X(6900)$. We predict their masses. It is possible that a few of these states have already been seen by LHCb.
欧洲核子研究中心的LHCb实验发现了一种双粲等夸克四夸克态$T_{cc}$，量子数为$c c \bar u \bar d$，质量约为3875 MeV/ $c^2$，通过中间通道$D^{*+} D^0$衰变为$D^0 D^0 π^+$。本文在忽略$q = u, d$和同位旋破坏的情况下，用$c c \bar q \bar s$的量子数研究了它的奇异伴子.
Deciphering the nature of $X(2300)$ with the PACIAE model
School of Physics and Information Technology, Shaanxi Normal University（陕西师范大学物理与信息技术学院）；School of Physics and Electronic Science, Guizhou Normal University（贵州师范大学物理与电子科学学院）；Wuhan Textile University（武汉纺织大学）；Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University（华中师范大学夸克与轻子物理教育部重点实验室及粒子物理研究所）；China Institute of Atomic Energy（中国原子能科学研究院）
An alternative way to decipher the nature of the doubly charmed tetraquark $T_{cc}(3875)^+$: its antiparticle $T_{{\bar c}{\bar c}}(3875)^-$ photoproduction off nuclei near threshold
Discovery of $T_{c\bar s 0}^a(2900)^{0,++}$ implies new charmed-strange pentaquark system
受LHCb合作组最近发现的四夸克态$T_{c\bar s 0}^a(2900)^{0,++}$的启发，我们预言了一个新的奇异五夸克态$c\bar s nnn$的存在，它通过用$n=u,d$将$\bar n$交换成$nn$而与$c\bar s n\bar n$紧密相连.特别是建议在质量谱和衰变性质研究的支持下，通过$B$介子或$b$ -重子的弱衰变，在实验上寻找预言的新的五夸克系统。预言的新五夸克体系在不久的将来构建“粒子动物园2.0”时，必将引起实验学家和理论家的广泛关注。
A Paradigm for the Coupled-Channel Origin of Resonances: the Exotic $T_{c\bar{s}}$ in $D_{s1}(2460/2536)\to D_sππ$
University of Electronic Science and Technology of China（电子科技大学）；High Energy Accelerator Research Organization (KEK)（高能加速器研究机构）；University of Chinese Academy of Sciences (UCAS)（中国科学院大学）；Japan Atomic Energy Agency（日本原子能机构）；RIKEN（理化学研究所）
