Higher order QCD calculations for collider phenomenology

在欧洲核子研究中心的大型强子对撞机（LHC）测量的大多数碰撞中，都会产生大量的粒子。然而，对于一类特殊的事件，即所谓的排他性事件，情况并非如此。如果潜在的硬散射是通过色中性交换发生的，就像光子或处于色单态的胶子系统一样，这种情况就可能发生。为了更好地理解这些事件，需要更高阶的计算。最近这样的工作已经完成（部分在利物浦）的矢量介子光生的特殊情况下，随后在LHCb的测量证实了预测。拟议的研究项目是对更复杂的开夸克（或喷流）产生情况进行计算，并可能对包括W、Z或希格斯玻色子的电产生或过程进行计算。这不仅有助于更深入地理解强相互作用，更好地约束质子的部分子分布函数（和重离子），但也将为粒子物理学的标准模型（SM）之外的物理学提供搜索渠道。第二个可能的项目，已经与Chris Flett讨论过，是参与微扰QCD的四阶计算，由NIKHEF（阿姆斯特丹）的Jos Vermaseren的ERC小组与利物浦的Andreas沃格特（第二位监督员）一起执行。这些计算处于理论高能物理中符号计算的前沿，其主要目的是约束并最终计算夸克和胶子的尺度依赖性的次-领先阶（NNNLO）分裂函数。质子中的胶子分布。NNNLO计算是必需的，例如，在欧洲核子研究中心的大型强子对撞机上希格斯粒子产生的截面，以及最好地确定强耦合常数，这是SM的基本参数之一。

In most collisions measured at the Large Hadron Collider (LHC) at CERN, a very large number of particles are produced. However, for a special class of events, so-called exclusive events, this is not the case. This can happen if the underlying hard scattering occurs through colour neutral exchanges, like photons or systems of gluons in the colour singlet state. To better understand these events, higher order calculations are required. Recently such work has been done (in part in Liverpool) for the special case of vector meson photo-production, and subsequently measurements at the LHCb have confirmed the predictions. The proposed research project is to perform calculations for the more complicated case of open quark (or jet) production, and possibly to electro-production or processes including W, Z or Higgs bosons. This will not only lead to a deeper understand of the strong interaction and to better constrain the parton distributions functions of the proton (and heavy ions), but will also provide search channels for physics beyond the Standard Model (SM) of particle physics.A second possible project, already discussed with Chris Flett, is to participate in fourth-order calculations in perturbative QCD, performed by the ERC group of Jos Vermaseren at NIKHEF (Amsterdam) together with Andreas Vogt in Liverpool who will be the second supervisor. The main thrust of these calculations, which are at the cutting edge of symbolic computation in theoretical high-energy physics, is to constrain and ultimately calculate the next-to-next-to-next-to-leading order (NNNLO) splitting functions for the scale dependence of the quark and gluon distributions in the proton. NNNLO calculations are required, for example, for the cross section for Higgs production at the LHC at CERN, and for the best possible determination of the strong coupling constant which is one of the fundamental parameters of the SM.