Enhanced breaking of heavy quark spin symmetry

Abstract

Heavy quark spin symmetry is useful to make predictions on ratios of decay or production rates of systems involving heavy quarks. The breaking of spin symmetry is generally of the order of $O({\Lambda }_{\mathrm{QCD}}/m_Q)$, with ${\Lambda }_{\mathrm{QCD}}$ the scale of QCD and $m_Q$ the heavy quark mass. In this paper, we will show that a small $S$- and $D$-wave mixing in the wave function of the heavy quarkonium could induce a large breaking in the ratios of partial decay widths. As an example, we consider the decays of the ${\rm Y}(10860)$ into the ${\chi }_{bJ}\omega (J=0,1,2)$, which were recently measured by the Belle Collaboration. These decays exhibit a huge breaking of the spin symmetry relation were the ${\rm Y}(10860)$ a pure $5S$ bottomonium state. We propose that this could be a consequence of a mixing of the $S$-wave and $D$-wave components in the ${\rm Y}(10860)$. Prediction on the ratio $\Gamma ({\rm Y}(10860)\to {\chi }_{b0}\omega )/\Gamma ({\rm Y}(10860)\to {\chi }_{b2}\omega )$ is presented assuming that the decay of the $D$-wave component is dominated by the coupled-channel effects.

13 pages, 5 figures. Discussion extended, version to appear in Phys.Lett.B

References in corpus (5)

• Effect of charmed meson loops on charmonium transitions
• Hadronic Decays of the X(3872) to chi_{cJ} in Effective Field Theory
• Confirming the molecular nature of the $Z_b(10610)$ and the $Z_b(10650)$
• Enhanced mixing of partial waves near threshold for heavy meson pairs and properties of $Z_b(10610)$ and $Z_b(10650)$ resonances
• Light quark mass dependence in heavy quarkonium physics

Cited by in corpus (8)

• Novel Method for Precisely Measuring the $X(3872)$ Mass
• Bottomonium-like states: physics case for energy scan above the $B\bar{B}$ threshold at Belle-II
• Observation of $e^{+}{e}^{-}\to \omega {\chi }_{bJ}(1P)$ and search for $X_b\to \omega {\rm Y}(1S)$ at $\sqrt{s}$ near 10.75 GeV
• Production of the spin partner of the X(3872) in e^+e^- collisions
• Decays of ${\rm Y}(10860)$ and ${\rm Y}(10753)$ into $\omega {\chi }_{bJ}$
• Exotic hadrons associated with $b$-quark
• Improved measurement of Born cross sections for ${\chi }_{bJ}\omega$ and ${\chi }_{bJ}({\pi }^{+}{\pi }^{-}{\pi }^0{)}_{\mathrm{non}-\omega }$ ($J$ = 0, 1, 2) at Belle and Belle II
• Holographic Heavy Quark Symmetry