色玻璃凝聚态下小$x$的夸克碎裂函数
Quark fracture function at small $x$ from the Color Glass Condensate
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中文总结 AI 辅助
本文在色玻璃凝聚态框架下推导小$x$夸克碎裂函数，发现其受胶子饱和影响，但强子化卷积会抹去该效应。
中文摘要 AI 辅助
深度非弹性电子-核散射中的靶碎裂区为研究靶的部分子结构提供了洞察，因为最终态中测量的强子保留了核内旁观部分子非微扰动力学的信息。在QCD因子化定理中，这种非微扰动力学被编码在称为碎裂函数的对象中。本文中，我们研究被撞击（反）夸克携带非常小的纵向动量分数$x$的极限下的扩展夸克碎裂函数。我们首先在色玻璃凝聚态有效场论中，基于偶极子算符，给出小$x$下夸克碎裂函数的一个初等推导。在部分子层面，当靶碎裂区产生的出射部分子的横动量$P_\perp$小于核饱和标度$Q_s$时，夸克扩展碎裂函数对胶子饱和效应敏感，在此区域$P_\perp$分布近似平坦。然后，通过一个包含该部分子级结果与共线碎裂函数卷积的数值研究，我们表明强子化在很大程度上抹去了这些饱和效应，因为卷积主要探测的是通常大于$Q_s$的部分子横动量。
英文摘要
The target-fragmentation region in deeply inelastic electron-nucleus scattering provides insight into the partonic structure of the target, as hadrons measured in the final state retain information about the nonperturbative dynamics of spectator partons inside the nucleus. In QCD factorization theorems, this nonperturbative dynamics is encoded in objects known as fracture functions. In this paper, we study the extended quark fracture function in the limit where the struck (anti)quark carries a very small longitudinal momentum fraction, $x$. We first present an elementary derivation within the Color Glass Condensate effective field theory of the quark fracture function in terms of the dipole operator at small $x$. At the parton level, the quark extended fracture function is sensitive to gluon saturation when the transverse momentum $P_\perp$ of the outgoing parton produced in the target-fragmentation region is smaller than the nuclear saturation scale $Q_s$, in which regime the $P_\perp$ distribution becomes approximately flat. We then show, through a numerical study that incorporates the convolution of this parton-level result with a collinear fragmentation function, that hadronization largely washes out these saturation effects, as the convolution predominantly probes partonic transverse momenta that are typically larger than $Q_s$.
