The future SIDIS measurement on transversely polarized deuterons by the COMPASS Collaboration
The future SIDIS measurement on transversely polarized deuterons by the COMPASS Collaboration
复制标题
COMPASS 协作组织未来对横向偏振氘核进行 SIDIS 测量
作者：
F. Bradamante
自 2005 年以来，通过 HERMES 和 COMPASS 实验对柯林斯和西弗斯不对称性的测量，可以评估横切率和西弗斯 PDF 不为零，并且可以在横向偏振目标上的半包容 DIS 中进行测量。大部分数据是在质子目标上收集的，在 COMPASS 实验的早期阶段仅在氘核 ($^6$LiD) 目标上收集了小事件样本，最近在 JLab 在 $^3$He 上收集了数据，因此 $d$-夸克和海夸克 PDF 比 $u$-夸克 PDF 更鲜为人知。这对核子横向自旋结构的认识构成了重要限制。因此，COMPASS 合作组织建议以良好的精度测量横向偏振氘核上的半包容 DIS，与现有的质子横向自旋不对称数据相当。该提案已被 CERN 接受，实验将于 2021 年 Long Shut-down 2 结束后进行，提供的测量结果将在未来许多年保持独特。将给出用于提取横切 PDF 的投影，以及用于评估核子等矢量张量电荷的投影。
Since 2005, measurements of Collins and Sivers asymmetries from the HERMES and COMPASS experiments have allowed to assess that the transversity and the Sivers PDFs are different from zero and measurable in semi-inclusive DIS on transversely polarised targets. Most of the data were collected on proton targets, only small event samples were collected in the early phase of the COMPASS experiment on a deuteron ($^6$LiD) target and more recently at JLab, on $^3$He, so that the $d$-quark and the sea-quarks PDFs are much more poorly known than the $u$-quark PDFs. This constitutes an important limitation to the knowledge of the transverse spin structure of the nucleon. For this reason the COMPASS Collaboration has proposed to measure semi-inclusive DIS on transversely polarised deuterons with good accuracy, comparable with that of the existing transverse spin asymmetry data on protons. The proposal has been accepted by CERN and the experiment will run in 2021, as soon as the Long Shut-down 2 is over, providing measurements which will stay unique for many years to come. Projections will be given for the extraction of the transversity PDFs, and for the evaluation of the isovector tensor charge of the nucleon.