The hidden-charm pentaquark and tetraquark states

By Hua-Xing Chen, Wei Chen, Xiang Liu, Shi-Lin Zhu. 2016

1,307 citations recorded by the source corpus.

In the past decade many charmonium-like states were observed experimentally. Especially those charged charmonium-like $Z_c$ states and bottomonium-like $Z_b$ states can not be accommodated within the naive quark model. These charged $Z_c$ states are good candidates of either the hidden-charm tetraquark states or molecules composed of a pair of charmed mesons. Recently, the LHCb Collaboration discovered two hidden-charm pentaquark states, which are also beyond the quark model. In this work, we review the current experimental progress and investigate various theoretical interpretations of these candidates of the multiquark states. We list the puzzles and theoretical challenges of these models when confronted with the experimental data. We also discuss possible future measurements which may distinguish the theoretical schemes on the underlying structures of the hidden-charm multiquark states.

Subfields: Atomic and Molecular Physics, and Optics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/90f5644b9a6c1e7d6a416115e8e3944dc78d3de0

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In Atomic and Molecular Physics, and Optics

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Citations in the corpus

Scattering processes and resonances from lattice QCD (2017, background): “Many of these, known colloquially as the “X,Y,Z ” states, have been found in the heavy quark sector (see (Chen et al., 2016; Lebed et al., 2017; Liu, 2014) for recent reviews on the topic), and a complete understanding of them remains elusive, with piecemeal proposals ranging from tetraquark…”
Heavy-quark QCD exotica (2016, methodology): “The num er of Xð3872Þ events (Nobs), radiative correction fa tor (1þ δ), detection efficiency (ϵ), measured Born cross section σB½eþe− → γ ð3872Þ& times B½Xð3872Þ → πþπ−J=ψ & (σB · B, where the first uncertainties are statistical and the second sy te atic), measured ISR ψð3686Þ cross section (σISR, ”
Hadronic molecules (2017, methodology): “…ion collisions (Wang et al., 2016b), pionnucleon reactions (Kim et al., 2016; Lin et al., 2017; Liu 16 and Oka, 2016b), or search for their strange (Chen et al., 2016d; Feijoo et al., 2015, 2016; Lu et al., 2016b; Ramos et al., 2016), neutral (Lebed, 2015; Lü et al., 2016) and bottomonium…”
The XYZ states: Experimental and theoretical status and perspectives (2019, background): “additional references are also provided in the review articles [84, 582].”
Multiquark Resonances (2016, background): “The readers more interested in experimental details are invited to look at [2, 4, 6, 294, 295].”
Exotic Hadrons: Review and Perspectives (2016, background): “, [151] for examples of early attempts, and [15, 17, 152] for some reviews of the state of art over the years.”
Exotics: Heavy pentaquarks and tetraquarks (2017, background): “However, as they have been covered extensively in reviews [16, 58], we will not discuss them here.”