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arXiv 2304.09356hep-ph
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LHC 固定靶相互作用中内禀粲产生的贡献

Contribution from Intrinsic Charm Production to Fixed-Target Interactions at the LHC

R. Vogt

AI总结:

本文在 LHCb SMOG 固定靶实验中,结合微扰 QCD 与内禀粲计算开粲和 J/ψ 产生,发现内禀粲贡献小且随能量减小,计算结果与现有数据吻合。

摘要:

背景:内禀粲,即强子波函数中的非微扰粲夸克,长期以来一直受到推测但从未得到令人满意的证实。LHCb 实验在固定靶构型下对开粲和 $J/ψ$ 的测量搜寻了这种贡献,但未报告任何证据。目的:针对 LHCb 实验中的 SMOG 固定靶构型,结合微扰 QCD 与内禀粲计算 $\overline D$ 介子和 $J/ψ$ 的产生,以检验内禀粲在 SMOG 运动学中是否确实可观测。方法:开粲和 $J/ψ$ 的产生在微扰 QCD 中计算至次领头阶。由于使用气体喷射核靶,冷核物质效应被纳入微扰计算。内禀粲的计算假设其产生来自 $|uud c \overline c \rangle$ 福克态。结果:在 SMOG 接受度内计算了 $p+{\rm Ne}$、$p+{\rm He}$ 和 $p+{\rm Ar}$ 固定靶相互作用中的微分快度和横动量分布,并与数据进行比较。还展示了 $\overline D$(领头粲)与 $D$(非领头粲)之间预测的不对称性。结论:内禀粲的贡献很小,并随质心能量的增加而减小。无论是否包含内禀粲,计算结果都与当前 SMOG 数据吻合良好。

英文摘要:

Background: Intrinsic charm, nonperturbative charm in the hadron wavefunction, has long been speculated but has never been satisfactorily proven. Open charm and $J/ψ$ measurements in a fixed-taget configuration at the LHCb searched for this contribution but reported no evidence. Purpose: $\overline D$ meson and $J/ψ$ production is calculated for the SMOG fixed-target configuration in the LHCb experiment using a combination of perturbative QCD and intrinsic charm to see whether intrinsic chaarm would indeed be observable in the SMOG kinematics. Methods: Open charm and $J/ψ$ production is calculated to next-to-leading order in perturbative QCD. Because a gas jet nuclear target is used, cold nuclear matter effects are included in the perturbative calculations. The intrinsic charm is calculated assuming production from a $|uud c \overline c \rangle$ Fock state. Results: The differential rapidity and transverse momentum distributions in $p+{\rm Ne}$, $p+{\rm He}$ and $p+{\rm Ar}$ fixed-target interactions are calculated in the SMOG acceptance and compared to data. The predicted asymmetries between $\overline D$ (leading charm) and $D$ (nonleading charm) are also shown. Conclusions: The contribution from intrinisic charm is small and decreases with center of mass energy. The calculations agree well with the current SMOG data, with or without intrinsic charm.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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