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Hadronic tensor molecule $B_c^{\ast +}B_c^{\ast -}$

S. S. Agaev, K. Azizi, H. Sundu

TL;DR

This work uses QCD sum rules to characterize the fully heavy hadronic tensor molecule MT = B_c^{*+} B_c^{*-} with J^PC = 2^{++}. A two-point sum-rule analysis yields the mass $m \approx 12.87$ GeV and current coupling $\Lambda \approx 6.70 \times 10^{-2}$ GeV$^{5}$, while a collection of three-point sum rules computes partial widths for a wide range of decay channels, including MT \to J/ψ Υ, MT \to η_b η_c, MT \to B_c^{(*)+} B_c^{(*)-}, and channels generated by $b\overline{b}$ annihilation. The total width is found to be $Γ_{MT} \approx 154$ MeV, indicating a relatively broad state that is kinematically allowed to decay into numerous heavy meson pairs. These predictions, including comparisons to tensor diquark scenarios, provide concrete targets for experimental searches at current and future colliders and help clarify the structure of fully heavy exotic hadrons.

Abstract

Mass and full decay width of the hadronic tensor molecule $\mathcal{M}_{ \mathrm{T}}=B_c^{\ast +}B_c^{\ast -}$ are examined in the framework of QCD sum rule method. To find the mass $m$ and current coupling $Λ$ of this state, we use the two-point sum rules. The result $(12.87 \pm 0.08)~\mathrm{ GeV}$ for $m$ indicates that $\mathcal{M}_{\mathrm{T}}$ can easily decay to pairs of $J/ψΥ$, $η_{b}η_{c}$, $B_{c}^{+}B_{c}^{-}$, and $ B_{c}^{\ast +}B_{c}^{\ast -}$ mesons. Kinematically permitted ways for $ \mathcal{M}_{\mathrm{T}}$ to transform to conventional mesons include also processes $\mathcal{M}_{\mathrm{T}} \to D^{(\ast)+}D^{(\ast )-}$, $D^{(\ast )0}\overline{D}^{(\ast )0}$, and $D_{s}^{(\ast)+}D_{s}^{(\ast)-}$ triggered by annihilation of $b\overline{b}$ quarks in the molecule. The decays to meson pairs $B^{(\ast)+}B^{(\ast )-}$, $B^{(\ast )0}\overline{B}^{(\ast )0}$ , and $B_{s}^{(\ast)0}\overline{B}_{s}^{(\ast )0}$ generated by $c\overline{c } \to $ light quarks are also among possible channels of the hadronic molecule $\mathcal{M}_{\mathrm{T}}$. Technical tools of the three-point sum rule approach are applied to compute partial widths of these decays. Our results for the mass and width $Γ_{\mathcal{M}_{\mathrm{T}}}=(154 \pm 19)~ \mathrm{MeV} $ of the tensor molecule $\mathcal{M}_{\mathrm{T}}$ are important for experimental studies of fully heavy exotic structures.

Hadronic tensor molecule $B_c^{\ast +}B_c^{\ast -}$

TL;DR

This work uses QCD sum rules to characterize the fully heavy hadronic tensor molecule MT = B_c^{*+} B_c^{*-} with J^PC = 2^{++}. A two-point sum-rule analysis yields the mass GeV and current coupling GeV, while a collection of three-point sum rules computes partial widths for a wide range of decay channels, including MT \to J/ψ Υ, MT \to η_b η_c, MT \to B_c^{(*)+} B_c^{(*)-}, and channels generated by annihilation. The total width is found to be MeV, indicating a relatively broad state that is kinematically allowed to decay into numerous heavy meson pairs. These predictions, including comparisons to tensor diquark scenarios, provide concrete targets for experimental searches at current and future colliders and help clarify the structure of fully heavy exotic hadrons.

Abstract

Mass and full decay width of the hadronic tensor molecule are examined in the framework of QCD sum rule method. To find the mass and current coupling of this state, we use the two-point sum rules. The result for indicates that can easily decay to pairs of , , , and mesons. Kinematically permitted ways for to transform to conventional mesons include also processes , , and triggered by annihilation of quarks in the molecule. The decays to meson pairs , , and generated by light quarks are also among possible channels of the hadronic molecule . Technical tools of the three-point sum rule approach are applied to compute partial widths of these decays. Our results for the mass and width of the tensor molecule are important for experimental studies of fully heavy exotic structures.

Paper Structure

This paper contains 14 sections, 100 equations, 4 figures, 1 table.

Table of Contents

  1. Introduction
  2. Spectroscopic parameters $m$ and $\Lambda$ of the molecule $\mathcal{M}_{\mathrm{T}}$
  3. Processes $\mathcal{M}_{\mathrm{T}}\rightarrow J/\psi \Upsilon$, $\eta _{b}\eta _{c}$
  4. Decay $\mathcal{M}_{\mathrm{T}}\rightarrow J/\psi \Upsilon$
  5. $\mathcal{M}_{\mathrm{T}}\rightarrow \eta _{b}\eta _{c}$
  6. Decays $\mathcal{M}_{\mathrm{T}}\rightarrow B_{c}^{\ast +}B_{c}^{\ast -}$ and $B_{c}^{+}B_{c}^{-}$
  7. $\mathcal{M}_{\mathrm{T}}\rightarrow B_{c}^{\ast +}B_{c}^{\ast -}$
  8. $\mathcal{M}_{\mathrm{T}}\rightarrow B_{c}^{+}B_{c}^{-}$
  9. Decays generated by $b\overline{b}$ annihilations
  10. Decays $\mathcal{M}_{\mathrm{T}}\rightarrow D^{\ast 0}\overline{D}^{\ast 0}$ and $D^{\ast +}D^{\ast -}$
  11. Processes $\mathcal{M}_{\mathrm{T}}\rightarrow D^{0}\overline{D}^{0}$ and $D^{+}D^{-}$
  12. Channels $\mathcal{M}_{\mathrm{T}}\rightarrow D_{s}^{+}D_{s}^{-}$ and $D_{s}^{\ast +}D_{s}^{\ast -}$
  13. Decays into $B$ meson pairs
  14. Discussion and conclusions

Figures (4)

  • Figure 1: The $\mathrm{PC}$ as a function of $M^{2}$ at various $s_{0}$. The border $\mathrm{PC}=0.5$ is plotted by the horizontal line. The red triangle fixes the point $M^{2}=9.5~\mathrm{GeV}^{2}$ and $s_{0}=185~\mathrm{GeV}^{2}$.
  • Figure 2: Mass $m$ as a function of the Borel $M^{2}$ (left panel), and continuum threshold $s_0$ parameters (right panel).
  • Figure 3: QCD data and fit functions for $g_{1}(Q^{2})$ (solid line) and $\overline{g}_{1}(Q^{2})$ (dashed line). The diamond fixes the point $Q^{2}=-m_{J/\psi }^{2}$ where $g_{1}$ and $\overline{g}_{1}$ have been estimated.
  • Figure 4: QCD data and extrapolating functions for the form factors $G_{1}(Q^{2})$ (dashed curve) and $G_{3}(Q^{2})$ (solid curve). The circle and diamond fix the points $Q^{2}=-m_{D^{\ast 0}}^{2}$ and $Q^{2}=-m_{D^{0}}^{2}$, respectively.