次领头功率因子化的喷注函数
Jet functions for next-to-leading power factorization
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中文总结 AI 辅助
该研究探讨部分子阈值附近散射过程的次领头功率因子化，在SCET和直接QCD方法中分析功率压低贡献，验证因子化公式，指出次领头功率对数重求和的两个挑战。
中文摘要 AI 辅助
我们讨论了部分子阈值附近散射过程在阈值变量1-z下的次领头功率（NLP）因子化，其中z≡q²/ŝ。我们回顾了软共线有效理论（SCET）和直接QCD方法中功率压低贡献的一般结构，并讨论了NLP喷注函数的定义，即QCD中规范不变的算符矩阵元。为了对所得因子化公式进行可控检验，我们利用区域方法，在m²≪s的极限下，对有质量电磁形状因子的一圈和两圈情况明确验证了该公式。最后，我们概述了次领头功率对数系统重求和仍存在的两个挑战：SCET卷积中端点发散的处理，以及将喷注函数扩展到能描述任意数量软胶子辐射的辐射过程——鉴于纯软 sector 已通过复制技巧以广义网的形式被理解，后者是指数化的最后缺失要素。
英文摘要
We discuss the factorization of scattering processes near partonic threshold at next-to-leading power (NLP) in the threshold variable $1-z$, with $z \equiv q^2/\hat{s}$. We review the general structure of power-suppressed contributions both in Soft-Collinear Effective Theory (SCET) and in a direct QCD approach, and discuss the definition of NLP jet functions as gauge-invariant operator matrix elements in QCD. As a controlled check of the resulting factorization formula, we verify it explicitly at one and two loops for the massive electromagnetic form factor in the limit $m^2 \ll s$, using the method of regions. We conclude by outlining the two challenges that remain for a systematic resummation of NLP logarithms: the treatment of endpoint divergences in SCET convolutions, and the extension of jet functions to radiative processes capable of describing an arbitrary number of soft-gluon emissions -- the latter being the last missing ingredient for exponentiation, given that the purely soft sector is already understood in terms of generalised webs via the replica trick.
