Multiquark Resonances

Abstract

Multiquark resonances are undoubtedly experimentally observed. The number of states and the amount of details on their properties has been growing over the years. It is very recent the discovery of two pentaquarks and the confirmation of four tetraquarks, two of which had not been observed before. We mainly review the theoretical understanding of this sector of particle physics phenomenology and present some considerations attempting a coherent description of the so called X and Z resonances. The prominent problems plaguing theoretical models, like the absence of selection rules limiting the number of states predicted, motivate new directions in model building. Data are reviewed going through all of the observed resonances with particular attention to their common features and the purpose of providing a starting point to further research.

Version published on Physics Reports

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• How Resonances can synchronise with Thresholds
• Employing spin symmetry to disentangle different models for the XYZ states
• Studying the P_c(4450) resonance in J/psi photoproduction off protons
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• Indications of a Four-Quark Structure for the X(3872) and X(3876) Particles from Recent Belle and BABAR Data
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• Tetraquark spectroscopy
• Charmonium spectroscopy above thresholds
• Chromomagnetism, flavour symmetry breaking and S-wave tetraquarks
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• Estimating the Production Rate of Loosely-bound Hadronic Molecules using Event Generators
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• Are There Tetraquarks at Large $N_c$ in QCD(F)?
• Charged charmonium-like Z+(4430) from rescattering in conventional B decays
• Spectra and decays of hybrid charmonia
• Ordinary and Extraordinary Hadrons
• Interpretations for the X(4160) observed in the double charm production at B factories
• Probing the nature of Z_c states via the eta_c rho decay
• Heavy quark symmetry and weak decays of the $b$-baryons in pentaquarks with a $c\bar{c}$ component
• Non-ordinary light meson couplings and the $1/N_c$ expansion
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• On the Spin of the X(3872)
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• On the constituent counting rules for hard exclusive processes involving multiquark states
• A note on the newly observed Y(4220) resonance
• ${\chi }_{c0}\omega$ production in $e^{+}{e}^{-}$ annihilation through $\psi (4160)$
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Cited by in corpus (34)

• Pentaquark and Tetraquark states
• Exotics: Heavy Pentaquarks and Tetraquarks
• Heavy-quark symmetry implies stable heavy tetraquark mesons $Q_i{Q}_j{\bar{q}}_k{\bar{q}}_l$
• Heavy quark spin symmetric molecular states from ${\bar{D}}^{(\ast )}{\Sigma }_c^{(\ast )}$ and other coupled channels in the light of the recent LHCb pentaquarks
• Anatomy of the newly observed hidden-charm pentaquark states: $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$
• Exotic tetraquark states with the $qq\bar{Q}\bar{Q}$ configuration
• Isospin breaking decays as a diagnosis of the hadronic molecular structure of the $P_c(4457)$
• Lattice QCD investigation of a doubly-bottom $\bar{b}\bar{b}ud$ tetraquark with quantum numbers $I(J^P)=0(1^{+})$
• A Theory of X and Z Multiquark Resonances
• Implications of Heavy Quark-Diquark Symmetry for Excited Doubly Heavy Baryons and Tetraquarks
• Three-body Unitarity with Isobars Revisited
• Tetraquark operators in lattice QCD and exotic flavour states in the charm sector
• Stability of tetrons
• Treating $Z_c(3900)$ and $Z(4430)$ as the ground-state and first radially excited tetraquarks
• The Dynamical Diquark Model: First Numerical Results
• Prediction of exotic doubly charmed baryons within chiral effective field theory
• Mass spectra for $qc\bar{q}\bar{c}$, $sc\bar{s}\bar{c}$, $qb\bar{q}\bar{b}$, $sb\bar{s}\bar{b}$ tetraquark states with $J^{PC}=0^{++}$ and $2^{++}$
• Spectroscopy of Exotic Hadrons Formed from Dynamical Diquarks
• Triply heavy tetraquark states with the $QQ\bar{Q}\bar{q}$ configuration
• Production of exotic tetraquarks $QQ\bar{q}\bar{q}$ in heavy-ion collisions at the LHC
• Re-examining the $X(4630)$ resonance in the reaction $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$
• The Hydrogen Bond of QCD
• Tetraquark and two-meson states at large $N_{\mathrm{c}}$
• Triply heavy $QQ\bar{Q}\bar{q}$ tetraquark states
• Tetraquarks in holographic QCD
• Spectroscopic parameters and decays of the resonance $Z_b(10610)$
• Narrow pentaquarks as diquark-diquark-antiquark systems
• The $\varphi (2170)$ production in the process $\gamma p\to \eta \varphi p$
• Weak Decays of Stable Open-bottom Tetraquark by SU(3) Symmetry Analysis
• Charmed baryon$-$nucleon interaction
• Decay $X(3872)\to {\pi }^0{\pi }^{+}{\pi }^{-}$ and $S$-wave $D^0{\bar{D}}^0\to {\pi }^{+}{\pi }^{-}$ scattering length
• Hidden charm pentaquark and $\Lambda (1405)$ in the ${\Lambda }_b^0\to {\eta }_c{K}^{-}p(\pi \Sigma )$ reaction
• Quark model description of $\psi (4260)$
• Analysis of the strong vertexes of ${\Sigma }_c^{\ast }ND$ and ${\Sigma }_b^{\ast }NB$ in QCD sum rules