论文标题
QCD分析电磁dalitz衰减$ j/ψ\rightarrowη^{（\ prime）} \ ell^{+el^{+} \ ell^{ - } $
QCD analysis of electromagnetic Dalitz decays $J/ψ\rightarrowη^{(\prime)}\ell^{+}\ell^{-}$
论文作者
论文摘要
电磁dalitz衰减$ j/ψ\rightArrowη^{（\ prime）} e^{+} e^{ - } $，在扰动QCD的框架内研究了具有大的后坐力动量。同时，通过软波函数的重叠描述了小后坐力动量区域的软贡献，共振贡献由向量中膜优势模型估算。基于此动态图片，首次计算出全运动区域中的过渡形式因子$ f_ {ψη^{（\ prime）}}}（q^{2}）$，首次计算出来，我们发现过渡形式的颜色对$η^{（\ prime）} $ amplitudes的形状不敏感。我们对归一化过渡形式的预测$ f_ {ψη}（q^{2}）\ equiv f_ {ψη}（q^{2}）/f_ {ψη}（0）$符合其实验数据。此外，我们还发现分支比率$ \ MATHCAL {B}（J/ψ\rightArrowη^{（（\ prime）} e^{+} e^{ - }）$由扰动QCD的贡献支配，并且共振贡献的贡献非常小，并且由于抑制了较小的抑制作用。有了所有这些贡献，我们的分支比率的结果$ \ MATHCAL {B}（J/ψ\rightArrowη^{（\ prime）} e^{+} e^{ - }） $ r_ {j/ψ}^{e} = \ Mathcal {b}（j/ψ\rightarrowηe^{+} e^{ - }）/\ Mathcal {b}（j/ψ\ rightArrowH^\rightArlOWη^{\ prime} e^{\ prime}使用获得的$ f_ {ψη^{（\ prime）}}}（q^{2}）$，我们给出了分支比率$ \ MATHCAL {b}（j/ψ\rightArrowη^{（（\ prime）} nim} g {+} g {+} {+} g { - } $ an的$ rat and的预测。
The electromagnetic Dalitz decays $J/ψ\rightarrowη^{(\prime)}e^{+}e^{-}$ with large recoil momentum are studied in the framework of perturbative QCD. Meanwhile, the soft contributions from the small recoil momentum region are described by the overlap of soft wave functions, and the resonance contributions are estimated by the vector meson dominance model. Based on this dynamical picture, the transition form factors $f_{ψη^{(\prime)}}(q^{2})$ in full kinematic region are calculated for the first time, and we find that the transition form factors are insensitive to the shapes of $η^{(\prime)}$ distribution amplitudes. Our prediction of the normalized transition form factor $F_{ψη}(q^{2})\equiv f_{ψη}(q^{2})/f_{ψη}(0)$ agrees well with its experimental data. In addition, we also find that the branching ratios $\mathcal{B}(J/ψ\rightarrowη^{(\prime)}e^{+}e^{-})$ are dominated by the contributions of perturbative QCD, and the resonance contributions are negligibly small as well as the soft contributions due to the suppression of the kinematic factor. With all these contributions, our results of the branching ratios $\mathcal{B}(J/ψ\rightarrowη^{(\prime)}e^{+}e^{-})$ and the ratio $R_{J/ψ}^{e}=\mathcal{B}(J/ψ\rightarrowηe^{+}e^{-})/\mathcal{B}(J/ψ\rightarrowη^{\prime}e^{+}e^{-})$ are in good agreement with their experimental data. Using the obtained $F_{ψη^{(\prime)}}(q^{2})$, we give the predictions of the branching ratios $\mathcal{B}(J/ψ\rightarrowη^{(\prime)}μ^{+}μ^{-})$ and their ratio $R_{J/ψ}^μ$.
