标题： 纯DVCS交叉截面在COMPASS中的$t$依赖性 显示英文标题

标题： The $t$-dependence of the pure DVCS cross section at COMPASS

摘要： 研究广义部分子分布的关键反应是深度虚拟康普顿散射（DVCS）和深度虚拟介子产生（DVMP）。在COMPASS实验中，这些过程是使用动量为160 GeV/c的高强度缪子束流和一个2.5米长的液氢靶进行研究的。为了在这些能量下优化独占反应的选择，靶周围安装了一个新的桶形飞行时间系统，用于探测反冲粒子。COMPASS-II覆盖了目前尚未探索的$x_{B}$区域，范围从0.01到0.15。通过正负束流极化测量的截面之和，提取了纯DVCS截面及其$t$依赖性，从而首次在平均$x_{B}$值为0.056的情况下，独立于模型确定了核子部分子分布的横向尺寸$\sqrt{<r_{\perp}^2>}= (0.578 \ \pm \ 0.042\ _{- \ 0.018}^{+ \ 0.006})\,\textsf{fm} $。 显示英文摘要

摘要： The key reactions to study the Generalised Parton Distributions are Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP). At COMPASS, these processes are investigated using a high intensity muon beam with a momentum of 160\,GeV/c and a 2.5\,m-long liquid hydrogen target. In order to optimize the selection of exclusive reactions at these energies, the target is surrounded by a new barrel-shaped time-of-flight system to detect the recoiling particles. COMPASS-II covers the up to now unexplored $x_{B}$ domain ranging from 0.01 to 0.15. From the sum of cross sections measured with positive and negative beam polarities, the pure DVCS cross-section and its $t$-dependence have been extracted resulting in a first model-independent determination of the transverse size of the partonic distribution of the nucleon $\sqrt{<r_{\perp}^2>}= (0.578 \ \pm \ 0.042\ _{- \ 0.018}^{+ \ 0.006})\,\textsf{fm} $ at a mean $x_{B}$ value of 0.056.