arXiv 1703.097022017-03hep-ph

排他Drell-Yan模型中大质量夸克效应的因子化和恢复

Factorization and Resummation for Massive Quark Effects in Exclusive Drell-Yan

Piotr Pietrulewicz, Daniel Samitz, Anne Spiering, Frank J. Tackmann

备注：: 42 pages + appendices, 21 figures; v2: journal version
DOI：: 10.1007/JHEP08(2017)114

摘要：

强子对撞机上色单态过程的排他性微分谱是理论和实验上都得到了高精度研究的基准观测量。我们提出了一个有效的理论框架，利用软共线有效理论将大量（底）夸克的影响纳入图解微分分布，占重夸克发起的硬散射过程的主要贡献，以及从胶子分裂成重夸克对的二次效应。具体来说，我们专注于Drell-Yan过程，并考虑矢量玻色子横动量，$q_T$，和梁推力，$\mathcal T$，作为排他性的可观测量的例子。理论描述取决于硬、质量和$q_T$（或$\mathcal T$）尺度之间的等级，范围从解耦极限$q_T \ll m$到无质量极限$m \ll q_T$。唯象相关的中间制度$m \sim q_T$，特别需要夸克质量相关的光束和软功能。我们计算所有成分的描述所需的主要和次要的质量效应在NNLL $'$再确认顺序（结合NNLL演变与NNLO边界条件）$q_T$和$\mathcal T$在所有相关的层次结构。对于$q_T$分布的快度发散是不同的无质量的情况下，我们讨论了由此产生的快度演化的功能。我们的结果将允许在小的$q_T$下详细研究$W$和$Z$玻色子谱的比例中的夸克质量效应，这对于在LHC上精确测量$W$ -玻色子质量是重要的。

英文摘要：

Exclusive differential spectra in color-singlet processes at hadron colliders are benchmark observables that have been studied to high precision in theory and experiment. We present an effective-theory framework utilizing soft-collinear effective theory to incorporate massive (bottom) quark effects into resummed differential distributions, accounting for both heavy-quark initiated primary contributions to the hard scattering process as well as secondary effects from gluons splitting into heavy-quark pairs. To be specific, we focus on the Drell-Yan process and consider the vector-boson transverse momentum, $q_T$, and beam thrust, $\mathcal T$, as examples of exclusive observables. The theoretical description depends on the hierarchy between the hard, mass, and the $q_T$ (or $\mathcal T$) scales, ranging from the decoupling limit $q_T \ll m$ to the massless limit $m \ll q_T$. The phenomenologically relevant intermediate regime $m \sim q_T$ requires in particular quark-mass dependent beam and soft functions. We calculate all ingredients for the description of primary and secondary mass effects required at NNLL$'$ resummation order (combining NNLL evolution with NNLO boundary conditions) for $q_T$ and $\mathcal T$ in all relevant hierarchies. For the $q_T$ distribution the rapidity divergences are different from the massless case and we discuss features of the resulting rapidity evolution. Our results will allow for a detailed investigation of quark-mass effects in the ratio of $W$ and $Z$ boson spectra at small $q_T$, which is important for the precision measurement of the $W$-boson mass at the LHC.

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