Is $Z_b(10610)$ a Molecular State?

Abstract

Whether molecular states indeed exist in nature has been disputed for a long time. Several new resonances have been observed in the recent experiments and they seem to be of exotic structures and some of them have been proposed to be molecular states. The very recent observation of $Z_b(10610)[(10608.4\pm 2.0)$ MeV] and $Z_b(10650)[(10653.2\pm 1.5)$ MeV] encourages the interpretation of multi-quark states. In the Beter-Salpeter (BS) approach, we study the possibility if two heavy mesons can form a molecular state by exchanging light mesons. Our results indicate that two heavy mesons can form an isospin singlet (I=0) bound state but cannot form an isospin triplet (I=1) when the contribution of $\sigma -$ exchange is reasonably small, i.e. as the coupling of $\sigma$ with mesons $g_{\sigma }$ takes the value given in previous literatures. Thus we conclude that the newly observed $Z_b(10610)$ should not be a molecular state, but a tetraquark state instead, at most, the fraction of the molecular state in the physical resonance $Z_b(10610)$ is tiny.

arXiv comment15 pages, 2 figures, an important reference added; Accepted by JHEP

References in corpus (24)

• Observation of a narrow charmonium-like state in exclusive B+ -> K+ pi+pi- J/psi decays
• Observation of a New Narrow Charmonium State in Exclusive B+-->K+ pi+pi- J/psi Decays
• Phenomenology of Heavy Meson Chiral Lagrangians
• Observation of a resonance-like structure in the pi^+- psi' mass distribution in exclusive B-->K pi^+- psi' decays
• Final State Interactions in Hadronic B Decays
• Observation of a near-threshold omega-J/psi mass enhancement in exclusive B-->K omega J/psi decays
• Resurrection of the Sigma Meson
• Heavy quark spin structure in Z_b resonances
• Observation of a new charmonium state in double charmonium production in e+ e- annihilation at \sqrt{s} ~ 10.6 GeV
• Insight into the Scalar Mesons from a Lattice Calculation
• Bound state nature of the exotic Z_b states
• X(3872) as a molecular DD* state in a potential model
• Tetraquark Interpretation of the Charged Bottomonium-like states Z_b^+-(10610) and Z_b^+-(10650) and Implications
• Nonperturbative study of generalized ladder graphs in a ϕ^2χtheory
• Could $Z_b(10610)$ be a $B^{\ast }\bar{B}$ molecular state?
• Possible S-wave Bound-States of Two Pseudoscalar Mesons
• Radiative decays of ϕ-meson and nature of light scalar resonances
• The Scalar Meson f0(980) in Heavy-Meson Decays
• Absolute Branching Fraction Measurements of Exclusive D^+ Semileptonic Decays
• Studying the scalar bound states of the $K\bar{K}$ system in the Bethe-Salpeter formalism
• Observation of two charged bottomonium-like resonances
• Exotic Charmonium and Bottomonium-like Resonances
• Radiative decays of phi-meson about nature of light scalar resonances
• $B^{(\ast )}{\bar{B}}^{(\ast )}$ intermediate state contribution to ${\rm Y}(4S,5S)\to {\eta }_b+\gamma$ radiative decay

Cited by in corpus (28)

• Reanalysis of the $Y(3940)$, $Y(4140)$, $Z_c(4020)$, $Z_c(4025)$ and $Z_b(10650)$ as molecular states with QCD sum rules
• The $Z_b(10610)$ and $Z_b(10650)$ as axial-vector tetraquark states in the QCD sum rules
• Confirming the molecular nature of the $Z_b(10610)$ and the $Z_b(10650)$
• Study of the $B{\bar{B}}^{\ast }/D{\bar{D}}^{\ast }$ bound states in a Bethe-Salpeter approach
• The line shapes of the $Z_b(10610)$ and $Z_b(10650)$ in the elastic and inelastic channels revisited
• Tetraquark state $X(6900)$ and the interaction between diquark and antidiquark
• Study of $B{\bar{B}}^{\ast }$ and $B^{\ast }{\bar{B}}^{\ast }$ interactions in $I=1$ and relationship to the $Z_b(10610)$, $Z_b(10650)$ states
• General considerations on the nature of $Z_b(10610)$ and $Z_b(10650)$ from their pole positions
• Is $Z_c(3900)$ a molecular state
• Possible Molecular States of $D^{(\ast )}{D}^{(\ast )}$ and $B^{(\ast )}{B}^{(\ast )}$ within the Bethe-Salpeter framework
• More hidden heavy quarkonium molecules and their discovery decay modes
• Production of charged heavy quarkonium-like states at the LHC and the Tevatron
• Heavy Flavour Physics and CP Violation at LHCb: a Ten-Year Review
• Analysis of the hidden-bottom tetraquark mass spectrum with the QCD sum rules
• Could $Z_c(4025)$ be a $J^P=1^{+}$ $D^{\ast }\overline{D^{\ast }}$ molecular state?
• Interpretation of $Z_b(10610)$ and $Z_b(10650)$ in the ISPE mechanism and the Charmonium Counterpart
• Possible molecular states of ${\bar{D}}^{\ast }{K}^{\ast }$ ($D^{\ast }{K}^{\ast }$) and the new exotic states $X_0(2900)$ and $X_1(2900)$ ($T_{cs0}^a(2900{)}^0$ and $T_{cs0}^a(2900{)}^{++}$)
• Spectroscopic parameters and decays of the resonance $Z_b(10610)$
• Understanding Y(4274) and X(4320) in the $J/\psi \varphi$ invariant mass spectrum
• Insights into $Z_b(10610)$ and $Z_b(10650)$ from dipion transitions from ${\rm Y}(10860)$
• Study on possible molecular states composed of ${\Lambda }_c\bar{D}$ (${\Lambda }_{b}B$) and ${\Sigma }_c\bar{D}$ (${\Sigma }_{b}B$) within the Bethe-Salpeter framework
• The $Z_b$ structures in a constituent quark model coupled-channels calculation
• Studying the $D_{1}D$ molecule in the Bethe-Salpeter equation approach
• Radially excited axial mesons and the enigmatic $Z_c$ and $Z_b$ in a coupled-channel model
• The study of possible molecular states of $D_s^{(\ast )}{D}_s^{(\ast )}$ and $B_s^{(\ast )}{B}_s^{(\ast )}$
• Search for supersymmetric baryons near production threshold in terms of the superflavor symmetry
• The possible $B\pi$ molecular state and its radiative decay
• Production of the bottomonium-like states $Z_b$ states at $e$-$h$ and ultraperipheral $h$-$h$ collisions