arXiv subjects

Ying-Zhao Jiang

Publications and source records attributed to Ying-Zhao Jiang.

6 recordsLinked to original sources

arXiv2026

Inclusive productions of $J/ψ+η_c$ in $e^{+}e^{-}$ annihilation at Belle

We study $e^{+}e^{-} \to J/ψ+η_c+X$ at next-to-leading order (NLO) in $α_s$ within the nonrelativistic QCD (NRQCD) framework to assess the color-octet (CO) mechanism at low energies. QCD corrections significantly enhance both color-singlet (CS) and CO leading-order results, with non-negligible QED-diagram contributions to the CS channel. At $Υ(4S)$, CO terms increase the inclusive cross section by $20\%$--$30\%$, and the enhancement grows rapidly with $\sqrt{s}$, yielding an energy dependence distinct from CS predictions and providing a sensitive test of NRQCD. Including $ψ(2S)$ feed-down further amplifies the NRQCD prediction by about $40\%$ at $Υ(4S)$. With Belle's reconstruction of $J/ψ\to μ^+μ^-$ and six $η_c$ decay channels, the process shows promising potential for observation.

hep-ph↗

arXiv2026

Next-to-leading order analysis of $J/ψ+ γ$ production in photon-photon collisions at CEPC

We systematically investigate the production of $J/ψ+ γ$ in $γγ$ collisions within nonrelativistic QCD (NRQCD) factorization, with the direct-photon channel calculated specifically up to the next-to-leading order in $α_s$. Calculations for CEPC energy region show the resolved photon contribution is negligible, while the direct photon process dominates, yielding substantial annual $J/ψ$ yields. Significant modifications to $J/ψ$ polarization parameters emerge from color-octet mechanisms, and different NRQCD long distance matrix elements (LDMEs) further yield distinct polarization patterns. Furthermore, the polarization predictions are highly sensitive to the $^3P_J^{[8]}$ LDME, while being insensitive to the $^1S_0^{[8]}$ and $^3S_1^{[8]}$ LDMEs. Leveraging the cleaner environment of $e^+e^-$ collisions versus hadronic processes, the production of $J/ψ$ associated with a photon in $γγ$ collisions provides a high-precision platform to test LDMEs universality and resolve longstanding $J/ψ$ polarization puzzles.

hep-ph↗

arXiv2024

Studies of $Z$ boson decay into double $Υ$ mesons at the NLO QCD accuracy

In this paper, we employ the nonrelativistic QCD factorization to conduct a comprehensive examination of the $Z$ boson decay into a pair of $Υ$ mesons, achieving accuracy at the next-to-leading-order (NLO) in $α_s$. Our calculations demonstrate that the QED diagrams are indispensable in comparison to the pure QCD diagrams, and the implementation of QCD corrections markedly enhance the QCD results, whereas it substantially diminish the QED results. To ensure consistency with the experimental methodology, we have taken into account the feed-down transitions originating from higher excited states, which exhibit significant relevance. Combining all the contributions, we arrive at the NLO prediction of $\mathcal{B}_{Z \to Υ(nS)+Υ(mS)} \sim 10^{-11}$, which is notably lower than the upper limits set by CMS.

hep-ph↗

arXiv2022

$X(3860)$ production in association with $J/ψ$ via $e^{+}e^{-}$ annihilation at Belle

In this paper, we study the $X(3860)$ production associated with $J/ψ$ via $e^{+}e^{-}$ annihilation at the next-to-leading-order (NLO) QCD accuracy, within the nonrelativistic QCD (NRQCD) framework. Under the hypothesis of $J^{PC}_{X(3860)}=0^{++}$, the predicted total cross sections agree well with the Belle's measurements at $\sqrt{s}=Υ(4S,5S)$, while the theoretical results given by the $2^{++}$ hypothesis significantly undershoot the data. This is consistent with the Belle's conclusion that the $0^{++}$ hypothesis is favored over the $2^{++}$ hypothesis for $X(3860)$. Despite the agreement of the total cross sections, the NRQCD predictions seem to be incompatible with the Belle-measured $J/ψ$ angular distributions. We also perform the NLO calculations of $σ_{e^{+}e^{-} \to J/ψ+X(3940)}$ on the assumption of $J^{PC}_{X(3940)}=0^{-+}$, discovering that the NRQCD predictions that coincide with the light-cone results are in good agreement with the experiment.

hep-ph↗

arXiv2022

Impact of $Z \to η_{c,b}+g+g$ on the inclusive $η_{c,b}$ meson yield in $Z$-boson decay

In this paper, we carry out the next-to-leading-order QCD corrections to $Z \to η_Q+g+g~(Q=c,b)$ (labeled as $gg$) through the color-singlet (CS) state of $Q\bar{Q}[^1S_0^{[1]}]$, with the aim of assessing the impact of this process on $Z$ bosons decaying into inclusive $η_Q$. We find that the QCD corrections to the $gg$ process can notably enhance its leading-order results, especially for the $η_c$ case, which would then greatly increase the existing predictions of $Γ_{Z \to η_Q+X}$ given by the CS-dominant process $Z \to η_{Q}[^1S_0^{[1]}]+Q+\bar{Q}$. Moreover, with these significant QCD corrections, the $gg$ process would exert crucial influence on the CS-predicted $η_Q$ energy distributions. In conclusion, in the CS studies of $Z \to η_Q+X$, besides $Z \to η_{Q}[^1S_0^{[1]}]+Q+\bar{Q}$, $Z \to η_Q[^1S_0^{[1]}]+g+g$ can provide phenomenologically indispensable contributions as well.

hep-ph↗

arXiv2022

Doubly-charmed baryon production in $Z$ boson decay

In this paper, we carry out a detailed study of doubly-charmed baryon production in $Z$ boson decay, on the basis of the nonrelativistic QCD factorization. With the inclusion of the di-quark states $(cc)[^3S_1]_{\bar{\textbf{3}}}$ and $(cc)[^1S_0]_{\textbf{6}}$, the branching ratio of $\mathcal{B}_{Z \to Ξ_{cc}+X}$ is predicted to be of the $10^{-5}$ order, indicating its experimental measurability. By comparing to the $Λ^{+}_{c}$ yield in $Z$ decay, we predict $\mathcal{R}_{Ξ_{cc}^{+}}(=\frac{Γ(Z \to Ξ^{+}_{cc}) \times \mathcal{B}(Ξ^{+}_{cc} \to Λ_c^{+}K^{-}π^{+})}{Γ(Z \to Λ_c^{+})})=(0.85^{+0.10}_{-0.07}) \times 10^{-4}$ and $\mathcal{R}_{Ξ_{cc}^{++}}(=\frac{Γ(Z \to Ξ^{++}_{cc}) \times \mathcal{B}(Ξ^{++}_{cc} \to Λ_c^{+}K^{-}π^{+}π^{+})}{Γ(Z \to Λ_c^{+})})=(1.70^{+0.20}_{-0.14}) \times 10^{-4}$, which are at clear variance with the SELEX measurements but comparable with the values given by the LHCb and Belle collaborations.

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