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Axial-vector molecules $ΥB_{c}^{-}$ and $η_{b}B_{c}^{\ast-} $

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

TL;DR

The paper analyzes axial-vector fully heavy hadronic molecules $ΥB_c^{-}$ and $η_b B_c^{*-}$ using QCD sum rules, predicting nearly identical masses around $m=(15800±90)$ MeV and showing they are unstable against dissociation into $ΥB_c^{-}$ or $η_b B_c^{*-}$. It derives dominant decay couplings via three-point sum rules, obtaining $Γ(M_{AV}\to ΥB_c^{-})=(46.9±13.3)$ MeV and $Γ(M_{AV}\to η_b B_c^{*-})=(31.7±9.5)$ MeV, and computes subleading bb annihilation channels with total width $Γ(M_{AV})=(112±17)$ MeV. The work demonstrates that subleading channels contribute substantially to the total width and provides detailed couplings for several final-state meson pairs, enabling experimental exploration of fully heavy molecular states. The results are compared with alternative models, showing compatibility within uncertainties and offering concrete predictions for experimental searches in ongoing and planned facilities.

Abstract

Axial-vector hadronic molecules $\mathcal{M}_{\mathrm{AV}}=ΥB_{c}^{-} $ and $\widetilde{\mathcal{M}}_{\mathrm{AV}}=η_{b}B_{c}^{\ast -} $ with the quark content $bb \overline{b}\overline{c}$ are studied using QCD sum rule method. The spectroscopic parameters of these molecules are computed in the context of the two-point sum rule method. Predictions for their masses are identical to each other and confirm that they are structures unstable against dissociations to ordinary heavy mesons. We evaluate the width of the state $\mathcal{M}_{\mathrm{AV}}$ and assume that it is equal to that of $\widetilde{\mathcal{M}}_{\mathrm{AV}} $. To this end, we explore its dominant decay channels $\mathcal{M}_{\mathrm{AV}} \to ΥB_{c}^{-} $ and $\mathcal{M}_{\mathrm{AV}} \to η_{b}B_{c}^{\ast -}$. There also are subleading modes of $\mathcal{M}_{\mathrm{AV}}$ generated due to annihilation of $\overline{b}b$ quarks. We consider decays of the molecule $\mathcal{M}_{\mathrm{AV}}$ to pairs of the mesons $B^{\ast -} \overline{D}^{0}$, $\overline{B}^{\ast 0} D^{-}$, $B^{-} \overline{D} ^{\ast 0}$, $\overline{B}^{0} D^{\ast -}$, $\overline{B}_{s}^{\ast 0} D_{s}^{-}$, and $\overline{B}_{s}^{0} D_{s}^{\ast -}$. To find strong couplings at the $\mathcal{M}_{\mathrm{AV}}$-meson-meson vertices which determine the partial widths of these processes, we apply QCD three-point sum rule approach. The mass $m=(15800 \pm 90)~\mathrm{MeV}$ and width $Γ[\mathcal{M}_{\mathrm{AV}}]=(112 \pm 17)~ \mathrm{MeV}$ of the molecule $ \mathcal{M}_{\mathrm{AV}}$ are useful for experimental studies of fully heavy molecular structures at ongoing and planning experiments.

Axial-vector molecules $ΥB_{c}^{-}$ and $η_{b}B_{c}^{\ast-} $

TL;DR

The paper analyzes axial-vector fully heavy hadronic molecules and using QCD sum rules, predicting nearly identical masses around MeV and showing they are unstable against dissociation into or . It derives dominant decay couplings via three-point sum rules, obtaining MeV and MeV, and computes subleading bb annihilation channels with total width MeV. The work demonstrates that subleading channels contribute substantially to the total width and provides detailed couplings for several final-state meson pairs, enabling experimental exploration of fully heavy molecular states. The results are compared with alternative models, showing compatibility within uncertainties and offering concrete predictions for experimental searches in ongoing and planned facilities.

Abstract

Axial-vector hadronic molecules and with the quark content are studied using QCD sum rule method. The spectroscopic parameters of these molecules are computed in the context of the two-point sum rule method. Predictions for their masses are identical to each other and confirm that they are structures unstable against dissociations to ordinary heavy mesons. We evaluate the width of the state and assume that it is equal to that of . To this end, we explore its dominant decay channels and . There also are subleading modes of generated due to annihilation of quarks. We consider decays of the molecule to pairs of the mesons , , , , , and . To find strong couplings at the -meson-meson vertices which determine the partial widths of these processes, we apply QCD three-point sum rule approach. The mass and width of the molecule are useful for experimental studies of fully heavy molecular structures at ongoing and planning experiments.

Paper Structure

This paper contains 10 sections, 69 equations, 5 figures, 1 table.

Table of Contents

  1. Introduction
  2. Spectroscopic parameters of the molecules $\mathcal{M}_{\mathrm{AV}}$ and $\widetilde{\mathcal{M}}_{\mathrm{AV}}$
  3. Decay of $\mathcal{M}_{\mathrm{AV}}$ to final states $\Upsilon B_{c}^{-}$ and $\eta _{b}B_{c}^{\ast -}$
  4. Decay $\mathcal{M}_{\mathrm{AV}}\rightarrow \Upsilon B_{c}^{-}$
  5. Process $\mathcal{M}_{\mathrm{AV}}\rightarrow \eta _{b}B_{c}^{\ast -}$
  6. Decays generated by annihilation of $\overline{b}b$ quarks
  7. $\mathcal{M}_{\mathrm{AV}}\rightarrow B^{\ast -}\overline{D}^{0}$, $\overline{B}^{\ast 0}D^{-}$
  8. $\mathcal{M}_{\mathrm{AV}}\rightarrow B^{-}\overline{D}^{\ast 0}$, $\overline{B}^{0}D^{\ast -}$
  9. $\mathcal{M}_{\mathrm{AV}}\rightarrow \overline{B}_{s}^{\ast 0}D_{s}^{-}$, $\overline{B}_{s}^{0}D_{s}^{\ast -}$
  10. Analysis and Final Notes

Figures (5)

  • Figure 1: The mass $m$ as a function of parameters $M^{2}$ at various $s_{0}$. Two vertical lines fix borders of $M^{2}$ inside of which restrictions imposed on $\Pi (M^{2},s_{0})$ are fulfilled.
  • Figure 2: Dependence of $\mathrm{PC}$ on the Borel parameter $M^{2}$ at fixed $s_{0}$. The circle shows the point $M^{2}=17.5~\mathrm{GeV}^{2}$ and $s_{0}=280.5~\mathrm{GeV}^{2}$.
  • Figure 3: The mass $m$ as a function of $M^{2}$ (left panel), and $s_0$ (right panel).
  • Figure 4: QCD data and extrapolating functions $\mathcal{F}_1 (Q^{2})$ (solid curve) and $\mathcal{F}_2 (Q^{2})$ (dashed line). The diamond and circle fix the points $Q^{2}=-m_{B_c}^{2}$ and $Q^{2}=-m_{B_{c}^{\ast}}^2$, respectively.
  • Figure 5: SR data for the form factors $G(Q^{2})$ and $\widehat{G}_{1}(Q^2)$ and fit functions $\overline{\mathcal{F}}(Q^{2})$ (solid line), $\widehat{\mathcal{F}}_1(Q^{2})$ (dash-dotted line). The circle and star are placed at positions $Q^{2}=-m_{\overline{D}^{0}}^{2}$ and $Q^{2}=-m_{D_{s}^{-}}^{2}$, respectively.