The past seventeen years have witnessed tremendous progress on the experimental and theoretical explorations of the multiquark states. The hidden-charm and hidden-bottom multiquark systems were reviewed extensively in [Phys. Rept. 639 (2016) 1-121]. In this article, we shall update the experimental and theoretical efforts on the hidden heavy flavor multiquark systems in the past three years. Especially the LHCb collaboration not only confirmed the existence of the hidden-charm pentaquarks but also provided strong evidence of the molecular picture. Besides the well-known $XYZ$ and $P_c$ states, we shall discuss more interesting tetraquark and pentaquark systems either with one, two, three or even four heavy quarks. Some very intriguing states include the fully heavy exotic tetraquark states $QQ\bar Q\bar Q$ and doubly heavy tetraquark states $QQ\bar q \bar q$, where $Q$ is a heavy quark. The $QQ\bar Q\bar Q$ states may be produced at LHC while the $QQ\bar q \bar q$ system may be searched for at BelleII and LHCb. Moreover, we shall pay special attention to various theoretical schemes. We shall emphasize the model-independent predictions of various models which are truly/closely related to Quantum Chromodynamics (QCD). There have also accumulated many lattice QCD simulations through multiple channel scattering on the lattice in recent years, which provide deep insights into the underlying structure/dynamics of the $XYZ$ states. In terms of the recent $P_c$ states, the lattice simulations of the charmed baryon and anti-charmed meson scattering are badly needed. We shall also discuss some important states which may be searched for at BESIII, BelleII and LHCb in the coming years.

中文翻译：

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五夸克态和四夸克态

过去的十七年见证了多夸克态的实验和理论探索的巨大进步。隐藏魅力和隐藏底部多夸克系统在 [Phys. 代表 639 (2016) 1-121]。在本文中，我们将更新过去三年在隐藏重味多夸克系统上的实验和理论工作。特别是 LHCb 合作不仅证实了隐藏魅力五夸克的存在，而且还提供了分子图片的有力证据。除了众所周知的 $XYZ$ 和 $P_c$ 状态外，我们还将讨论更有趣的四夸克和五夸克系统，它们具有一个、两个、三个甚至四个重夸克。一些非常有趣的状态包括全重奇异四夸克态 $QQ\bar Q\bar Q$ 和双重四夸克态 $QQ\bar q \bar q$，其中 $Q$ 是重夸克。$QQ\bar Q\bar Q$ 状态可能会在 LHC 上产生，而 $QQ\bar q \bar q$ 系统可能会在 BelleII 和 LHCb 上进行搜索。此外，我们将特别关注各种理论方案。我们将强调与量子色动力学（QCD）真正/密切相关的各种模型的独立模型预测。近年来，还通过晶格上的多通道散射积累了许多晶格 QCD 模拟，这些模拟提供了对 $XYZ$ 状态的基础结构/动力学的深入见解。就最近的 $P_c$ 状态而言，非常需要魅重子和反魅介子散射的晶格模拟。