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arXiv · 2107.02047

Next-to-leading-order study of $J/ψ$ angular distributions in $e^{+}e^{-} \to J/ψ+η_c,χ_{cJ}$ at $\sqrt{s} \approx 10.6$ GeV

Zhan Sun
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Abstract

In this paper, we present a detailed next-to-leading-order (NLO) study of $J/ψ$ angular distributions in $e^{+}e^{-} \to J/ψ+η_c,χ_{cJ}$ ($J=0,1,2$) within the nonrelativistic QCD factorization (NRQCD). The numerical NLO expressions for total and differential cross sections, i.e., $\frac{dσ}{d\cosθ}=A+B\cos^2θ$, are both derived. With the inclusion of the newly-calculated QCD corrections to $A$ and $B$, the $α_θ(= B/A)$ parameters in $J/ψ+χ_{c0}$ and $J/ψ+χ_{c1}$ are moderately enhanced, while the magnitude of ${α_θ}_{J/ψ+χ_{c2}}$ is significantly reduced; regarding the production of $J/ψ+η_c$, the $α_θ$ value remains unchanged. By comparing with experiment, we find the predicted ${α_θ}_{J/ψ+η_c}$ is in good agreement with the $\textrm{B}\scriptsize{\textrm{ELLE}}$ measurement; however, ${α_θ}_{J/ψ+χ_{c0}}$ is still totally incompatible with the experimental result, and this discrepancy seems to hardly be cured by proper choices of the charm-quark mass, the renormalization scale, and the NRQCD matrix elements.

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Zhan Sun. 2021-08-28. Next-to-leading-order study of $J/ψ$ angular distributions in $e^{+}e^{-} \to J/ψ+η_c,χ_{cJ}$ at $\sqrt{s} \approx 10.6$ GeV. https://doi.org/10.1007/jhep09(2021)073

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