$Z_b$ and $Z_c$ Exotic States as Coupled Channel Cusps

Abstract

It is demonstrated that the candidate tetraquark states $Z_b(10610)$, $Z_b(10650)$, $Z_c(3900)$, and $Z_c(4025)$ are coupled channel cusp effects. The model explains in a natural way the masses and quantum numbers of the putative states and the near equality of the widths of the $Z_b$ states. It is argued that the $Z_c(3900)$ and $Z_c(4025)$ should be visible in ${\bar{B}}^0\to J/\psi {\pi }^0{\pi }^0$ or $B^{-}\to J/\psi {\pi }^{-}{\pi }^0$, but should {\it not} appear in ${\bar{B}}^0\to J/\psi {\pi }^{+}{\pi }^{-}$, in agreement with recent LHCb results. Additional tests for cusp effects are suggested.

9 pages, 9 figures. Expanded discussion of previous work; expanded discussion of B decays; analysis of Zc(4025) added; additional implications added

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Cited by in corpus (47)

• Multiquark Resonances
• Pentaquark and Tetraquark states
• Exotics: Heavy Pentaquarks and Tetraquarks
• Chiral perturbation theory for heavy hadrons and chiral effective field theory for heavy hadronic molecules
• Explaining the Many Threshold Structures in the Heavy-Quark Hadron Spectrum
• Could the near-threshold $XYZ$ states be simply kinematic effects?
• Hadronic molecules in B decays
• $Z_{cs}(3985{)}^{-}$ as the $U$-spin partner of $Z_c(3900{)}^{-}$ and implication of other states in the ${\text{SU(3)}}_F$ symmetry and heavy quark symmetry
• The $X(4140)$, $X(4274)$, $X(4500)$ and $X(4700)$ in the relativized quark model
• Treating $Z_c(3900)$ and $Z(4430)$ as the ground-state and first radially excited tetraquarks
• Kinematical Cusp and Resonance Interpretations of the $X(2900)$
• The $Z_{cs}(3985)$ as a threshold effect from the ${\bar{D}}_s^{\ast }D+{\bar{D}}_s{D}^{\ast }$ interaction
• Compositeness of S-wave weakly-bound states from next-to-leading order Weinberg's relations
• Establishing the heavy quark spin and light flavor molecular multiplets of the $X(3872)$, $Z_c(3900)$ and $X(3960)$
• How to understand the underlying structures of $X(4140)$, $X(4274)$, $X(4500)$ and $X(4700)$
• A combined analysis of the $Z_c(3900)$ and the $Z_{cs}(3985)$ exotic states
• Productions of $X(3872)$, $Z_c(3900)$, $X_2(4013)$, and $Z_c(4020)$ in $B_{(s)}$ decays offer strong clues on their molecular nature
• Tetraquark Cusp Effects from Diquark Pair Production
• Excited and exotic bottomonium spectroscopy from lattice QCD
• Where are ${\chi }_{cJ}(3P)$?
• Threshold effects as the origin of $Z_{cs}(4000)$, $Z_{cs}(4220)$ and $X(4700)$ observed in $B^{+}\to J/\psi \varphi K^{+}$
• Relativistic description of asymmetric fully heavy tetraquarks in the diquark-antidiquark model
• Precise determination of the pole position of the exotic $Z_c(3900)$
• Reanalysis of the $X(4140)$ as axialvector tetraquark state with QCD sum rules
• Production of $Z_c(3900$) and $Z_c(4020)$ in $B_c$ decay
• The $Z_b$ structures in a constituent quark model coupled-channels calculation
• Double Exotic States Productions in Pion and Kaon Induced Reactions
• Density of States of a Coupled-Channel System
• Investigations on the light hadron decays of $Z_b(10610)$ and $Z_b(10650)$
• Charged charmoniumlike structures in the $e^{+}{e}^{-}\to \psi (3686){\pi }^{+}{\pi }^{-}$ process based on the ISPE mechanism
• Substructure of Multiquark Hadrons (Snowmass 2021 White Paper)
• Isospin analysis of $B\to D^{\ast }\bar{D}K$ and the absence of the $Z_c(3900)$ in $B$ decays
• Role of the short-range dynamics in the formation of $D^{(\ast )}{\bar{D}}^{(\ast )}/B^{(\ast )}{\bar{B}}^{(\ast )}$ hadronic molecules
• The role of triangle singularity in isospin breaking process $J/\psi \to \Lambda \bar{\Lambda }\pi$ and the possible evidence of ${\Sigma }^{\ast }({\frac{1}{2}}^{-})$ states
• $Z_c$ and $Z_{cs}$ systems with operator mixing at NLO in QCD sum rules
• Charmoniumlike Channels $1^{+}$ with Isospin $1$ from Lattice and Effective Field Theory
• Predictions for Bottomonium from a Relativistic Screened Potential Model
• Spin Partners of the $B^{(\ast )}{\bar{B}}^{(\ast )}$ resonances with a different approach than the Breit-Wigner parameterization
• Radiative decays of the neutral $Z_c(3900)$ and $Z_c(4020)$
• Interaction of exotic states in a hadronic medium: the $Z_c(3900)$ case
• Investigation of the $X(4020)$ peak in the $D^{\ast }{\bar{D}}^{\ast }$ and $\pi h_c$ channels
• Unexpected Mesons X, Y, Z, ... (tetraquarks? hadron molecules? ...)
• Analysis of the exotic resonances in the systems $QQ\bar{q}\bar{q}$ and $Qq\bar{Q}\bar{q}$ with the extended recoupling model
• Problems with meson spectroscopy involving perturbative loop corrections
• Unified coupled-channel description for the five near-threshold structures $\psi (3770)$, $G(3900)$, $R(3760)$, $R(3780)$ and $R(3810)$ from $e^{+}{e}^{-}$ annihilation
• The explanation of some exotic states in the $cs\bar{c}\bar{s}$ tetraquark system
• Decoding the near-threshold $X_{0,1}(4140)$ and $X_1(4685)$ states via OZI-suppressed coupled-channel scattering