解决 $J/ψ$ 强子产生中的普适性和极化之谜
Resolving the universality and polarization puzzles in $J/ψ$ hadroproduction
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中文总结 AI 辅助
通过阈值重求和解决 $J/ψ$ 强子产生中固定阶的普适性张力，并利用自旋翻转贡献解释弱极化现象。
中文摘要 AI 辅助
瞬发 $J/ψ$ 强子产生提出了两个相关之谜：固定阶强子分析和 $e^+e^-$ 分析对相同的色八重态（CO）长距离矩阵元（LDME）组合给出了不相容的约束，并且观测到的弱极化难以与产额同时重现。我们在碎裂函数形式中分析了高 $p_T$ 产生，并在非相对论量子色动力学（NRQCD）和软胶子因子化（SGF）两种框架下进行了前导对数阈值重求和。将重求和的强子产生拟合与重求和的 $e^+e^-$ 产生约束相结合，我们发现两种框架中存在一个共同的 LDME 区域，同时满足两个约束：阈值重求和解决了固定阶下存在的普适性张力。在该区域，$^{1}S_{0}^{[8]}$ 贡献很小，产额由 $^{3}S_{1}^{[8]}$ 和 $^{3}P_{J}^{[8]}$ 道主导，其领先横向贡献大部分相互抵消。这种抵消放大了 $^{3}S_{1}^{[8]}$ 道中的自旋对称性破缺跃迁，因此在单参数自旋翻转假设下，自然阶 $v^4$ 的贡献同时适应了测量的产额和弱极化。类似的敏感性也适用于 $\psi(2S)$ 产生。
英文摘要
Prompt $J/ψ$ hadroproduction poses two related puzzles: fixed-order hadronic and $e^+e^-$ analyses give incompatible constraints on the same color-octet (CO) long-distance matrix element (LDME) combination, and the weak observed polarization is difficult to reproduce together with the yield. We analyze high-$p_T$ production in the fragmentation-function formalism with leading-logarithmic threshold resummation in both nonrelativistic QCD (NRQCD) and soft-gluon factorization (SGF). Combining the resummed hadroproduction fit with bounds from resummed $e^+e^-$ production, we find in both frameworks a common LDME region satisfying the two constraints simultaneously: threshold resummation resolves the universality tension present at fixed order. There, the $^{1}S_{0}^{[8]}$ contribution is small and the yield is governed by the $^{3}S_{1}^{[8]}$ and $^{3}P_{J}^{[8]}$ channels, whose leading transverse contributions largely cancel. The cancellation amplifies spin-symmetry-breaking transitions in the $^{3}S_{1}^{[8]}$ channel, so that within a one-parameter spin-flip ansatz a contribution of natural order $v^4$ accommodates both the measured yields and the weak polarization. A similar sensitivity holds for $ψ(2S)$ production.
发表机构
- Jiangxi Normal University（江西师范大学）
- Peking University（北京大学）
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