All Heavy Tetraquarks: The Dynamical Diquark Model and Other Approaches

Abstract

The 2020 announcement by LHCb of a narrow structure $X(6900)$ in the di-$J/\psi$ spectrum -- a potential $c\bar{c}c\bar{c}$ state -- has opened a new era in hadronic spectroscopy. In this talk, we briefly survey theory works preceding this event, examine key features of the observed spectrum, and then discuss how subsequent theory studies (including with the author's own dynamical diquark model) have interpreted these features. We conclude with proposals for experiments capable of distinguishing competing interpretations.

arXiv comment7 pages, 1 figure. Invited talk at the 20th Lomonosov Conference on Elementary Particle Physics, 19-25 Aug. 2021

References in corpus (24)

• Heavy-Quark QCD Exotica
• Observation of structure in the $J/\psi$-pair mass spectrum
• Spectrum of fully-heavy tetraquarks from a diquark+antidiquark perspective
• Tetraquarks composed of 4 heavy quarks
• Double J/psi-meson Production at LHC and 4c-tetraquark state
• Coupled-channel interpretation of the LHCb double-$J/\psi$ spectrum and hints of a new state near the $J/\psi J/\psi$ threshold
• Towards the understanding of fully-heavy tetraquark states from various models
• Interpretation of structure in the di-$J/\psi$ spectrum
• Scalar Fully-heavy Tetraquark States $Q{Q}^{\prime }\bar{Q}\overline{Q^{\prime }}$ in QCD Sum Rules
• On the mechanism of $T_{4c}(6900)$ tetraquark production
• Fully-heavy tetraquarks in strongly interacting medium
• Insights into the inner structures of the fully charmed tetraquark state $X(6900)$
• Nature of $X(6900)$ and its production mechanism at LHCb
• Is the existence of a $J/\psi J/\psi$ bound state plausible?
• Spectrum of the Hidden-Bottom and the Hidden-Charm/Strange Exotics in the Dynamical Diquark Model
• Study of charmonium-like and fully-charm tetraquark spectroscopy
• Producing fully-charm structures in the $J/\psi$-pair invariant mass spectrum
• Deciphering the recently discovered tetraquark candidates around 6.9 GeV
• Some remarks on $X(6900)$
• Spectroscopy of Exotic Hadrons Formed from Dynamical Diquarks
• Hunting for tetraquarks in ultra-pheripheral heavy ion collisions
• A possible interpretation for $X(6900)$ observed in four-muon final state by LHCb -- A light Higgs-like boson?
• Observation of Feynman scaling violations and evidence for a new resonance at RHIC
• About the $J/\psi J/\psi$ peak of LHCb: fully-charmed tetraquark?