Exotic Heavy Quarkonium Spectroscopy: A Mini-review

Abstract

Since nine years experiments have been observing a host of exotic states decaying into heavy quarkonia. The interpretation of most of them still remains uncertain and, in some cases, controversial, notwithstanding a considerable progress has been made on the quality of the experimental information available and a number of ideas and models have been put forward to explain the observations. In this mini-review we will summarize the measurements, with the most recent updates, and list the useful ones yet to be done. We will discuss the problem of the spin of the X, which could hide some major surprise on its interpretation, and review some more phenomenological issues debated in the field.

14 pages, 2 figures, 5 tables. To appear in Mod. Phys. Lett. A

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• A new look at scalar mesons
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• Is the X(3872) Production Cross Section at Tevatron Compatible with a Hadron Molecule Interpretation?
• Evidence for the decay X(3872) --> J/psi omega
• Bounds on the width, mass difference and other properties of X(3872) --> pi+pi-J/psi decays
• Suppressed decay into open charm for the Y(4260) being an hybrid
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• Production of the X(3872) at the Tevatron and the LHC
• Measurement of the Dipion Mass Spectrum in X(3872) -> J/Psi Pi+ Pi- Decays
• Charmed Baryonium
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• Measurement of the e+e- --> b anti-b cross section between sqrt(S)=10.54 and 11.20 GeV
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• The 2^-+ assignment for the X(3872)
• More loosely bound hadron molecules at CDF?
• Relativistic model of hidden bottom tetraquarks
• Gluon fragmentation to ${}^1{D}_2$ quarkonia
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• On the Spin of the X(3872)
• X(3872) and Its Iso-Triplet Partners
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Cited by in corpus (45)

• Multiquark Resonances
• The Physics of the B Factories
• Four-Quark Hadrons: an Updated Review
• A J^PG=1++ Charged Resonance in the Y(4260) to pi+pi- J/psi Decay?
• Interpretation of the X(3872) as a charmonium state plus an extra component due to the coupling to the meson-meson continuum
• Could the near-threshold $XYZ$ states be simply kinematic effects?
• Higher mass bottomonia
• What can radiative decays of the X(3872) teach us about its nature?
• Heavy-quark spin symmetry partners of the $X(3872)$ revisited
• Strong $Z_c^{+}(3900)\to J/\psi {\pi }^{+};{\eta }_c{\rho }^{+}$ decays in QCD
• Interpreting $Z_c(3900)$ and $Z_c(4025)/Z_c(4020)$ as charged tetraquark states
• Mass and decay constant of the newly observed exotic $X(5568)$ state
• Doubly Charmed Tetraquarks in B_c and Xi_bc Decays
• Magnetic dipole moments of the $T_{cc}^{+}$ and $Z_V^{++}$ tetraquark states
• Width of the exotic $X_b(5568)$ state through its strong decay to $B_s^0{\pi }^{+}$
• 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
• Charmed partner of the exotic $X(5568)$ state and its properties
• Magnetic and quadrupole moments of the $Z_c(3900)$
• Electromagnetic multipole moments of the $P_c^{+}(4380)$ pentaquark in light-cone QCD
• Magnetic dipole moment of the $Z_{cs}(3985)$ state: diquark-antidiquark and molecular pictures
• Importance of meson-meson and of diquark-antidiquark creation operators for a $\bar{b}\bar{b}ud$ tetraquark
• Exploring the electromagnetic properties of the ${\Xi }_c^{(\prime ,\ast )}{\bar{D}}_s^{\ast }$ and ${\Omega }_c^{(\ast )}{\bar{D}}_s^{\ast }$ molecular states
• Application of the QCD light cone sum rule to tetraquarks: the strong vertices $X_b{X}_b\rho$ and $X_c{X}_c\rho$
• Electromagnetic properties of doubly heavy pentaquark states
• Open charm-bottom scalar tetraquarks and their strong decays
• Magnetic dipole moments of the $Z_c(4020{)}^{+}$, $Z_c(4200{)}^{+}$, $Z_{cs}(4000{)}^{+}$ and $Z_{cs}(4220{)}^{+}$ states in light-cone QCD
• Magnetic dipole moment of $Z_b(10610)$ in light-cone QCD
• Radiative decays and magnetic moments of the predicted $B_c$-like molecules
• X(3872) and Its Heavy Quark Spin Symmetry Partners in QCD Sum Rules
• The electromagnetic multipole moments of the charged open-flavor $Z_{\bar{c}q}$ states
• Resonance $X(5568)$ as an exotic axial-vector state
• A note on the newly observed Y(4220) resonance
• Probing an axial-vector tetraquark $Z_s$ via its semileptonic decay $Z_s\to X(4274)\overline{l}{\nu }_l$
• Magnetic moments of the vector hidden-charmed tetraquark states
• Probing exotic $J^{PC}$ resonances from deeply bound charmoniumlike molecules: Insights for identifying exotic hadrons
• The electromagnetic multipole moments of the possible charm-strange pentaquarks in light-cone QCD
• Magnetic and quadrupole moments of the $Z_c(4020{)}^{+}$, $Z_c(4050{)}^{+}$, and $Z_c(4600{)}^{+}$ states in the diquark-antidiquark picture
• Hamiltonian, Path Integral and BRST Formulations of Large N Scalar $QC{D}_2$ on the Light-Front and Spontaneous Symmetry Breaking
• Are there near-threshold Coulomb-like Baryonia?
• Mass Spectrum of Exotic X(5568) State via Artificial Neural Network
• Exploring the Spectrum of Heavy Quarkonium Hybrids with QCD Sum Rules
• Electromagnetic properties of the $D{\bar{D}}^{\ast }K$ molecular hexaquark state
• Investigating full-heavy tetraquarks composed of $cc\bar{c}\bar{b}$ and $bb\bar{b}\bar{c}$
• Production of exotic hadrons at hadron colliders