Multiparton interactions and higher-twist effects

这个项目致力于研究在硬尺度上对形式上具有分频功率的散射过程的贡献。超越领先的功率精度的重要性得到了广泛的认可。一个原因是，这些贡献限制了基于主导功率(主导扭曲)因式分解定理的QCD描述的最终准确性。他们需要被理解，以使理论与下一代实验设施所期望的非常高的数据精度相匹配。这尤其涉及EIC和JLAB12物理项目核心的排他性和半包容性反应，其中大部分数据现在和将来都将集中在适度的动量转移上。另一个原因是，高扭度的贡献实际上在相空间的某些区域变得不受抑制。强子-强子碰撞中的多子散射过程就是一个很好的例子。由于它们的重要性随着碰撞能量的增加而增加，它们在大型强子对撞机上引起了相当大的兴趣(在未来可能的强子对撞机上更是如此)。高扭曲效果的主题非常多样化，涵盖了许多不同的过程和方法。在第二个资助期，我们集中研究双部分子分布和对深度虚化康普顿散射的高扭度修正。本项目的研究补充了项目P1、P2和P4的高阶摄动改正的计算，目的是实现基准观测值的尽可能高的精度。

This project is devoted to the study of contributions to scattering processes that are formally of subleading power in the hard scale. The importance of going beyond the leading power accuracy is widely recognized. One reason is that such contributions constrain the ultimate accuracy of QCD description based on leading-power (leading-twist) factorization theorems. They need to be understood for the theory to match the very high data accuracy expected at the experimental facilities of the next generation. This concerns especially exclusive and semi-inclusive reactions at the heart of the physics programs of the EIC and JLAB12, where the bulk of data is and will be concentrated at moderate momentum transfers. Another reason is that higher-twist contributions actually become unsuppressed in certain regions of phase space. A prime example is provided by multiparton scattering processes in hadron-hadron collisions. As their importance grows with the collision energy, they are of considerable interest at the LHC (and even more so at possible future hadron colliders). The subject of higher twist effects is very diverse and covers a large variety of processes and methods. In the second funding period, we concentrate on the study of double parton distributions and on higher-twist corrections to the deeply-virtual Compton scattering. The studies in this project complement the calculation of higher-order perturbative corrections in projects P1, P2 and P4 with the goal to achieve highest possible precision for benchmark observables.