Precise predictions for vector-boson scattering at hadron colliders

随着2012年大型强子对撞机（LHC）发现希格斯玻色子，基本粒子物理学标准模型中最后一个缺失的粒子已经建立起来。希格斯玻色子通过电弱对称性破缺机制，为标准模型中的粒子提供了观测到的质量，同时保证了理论的统一性。电弱矢量玻色子的散射是研究这一机制最重要的关键过程，可以在大型强子对撞机上进行高精度测量。由于与标准模型的偏差可能很小，因此需要精确的理论预测来对这些过程进行彻底的分析。本研究计划的中心目标是计算标准模型中矢量玻色子散射的次一级修正。因此，电弱相互作用的修正也将首次在实际设置中确定这类过程。我们发现，电弱修正将大型强子对撞机对矢量玻色子散射的预测改变了几十个百分点，因此对实验数据的正确描述至关重要。因此，我们计划在大型强子对撞机上计算所有相关的矢量-玻色子散射过程的这些修正。我们将不仅考虑矢量玻色子散射的真实矩阵元素，而且在完整的标准模型中包括完整的树级和单环贡献集，这些贡献有助于相关的六粒子最终态。为了评估这些复杂过程的微扰修正，必须开发适当的方法。除了标准模型中的高阶修正外，我们还将通过适当的有效耦合考虑来自标准模型之外的影响。如果在不久的将来在大型强子对撞机上观测到指向标准模型特定扩展的新物理，我们的计算可以适应相应的模型。

With the discovery of the Higgs boson at the Large Hadron Collider (LHC) in 2012, the last missing particle of the standard model of elementary particle physics has been established. Via the mechanism of electroweak symmetry breaking, the Higgs boson provides the observed masses for the particles of the standard model and guarantees at the same time the unitarity of the theory. The scattering of electroweak vector bosons is the most important key process to study this mechanism and can be measured at the LHC with high precision. Since the deviations from the standard model might be small, precise theoretical predictions are required for a thorough analysis of these processes. The central goal of this research proposal is the calculation of next-to-leading-order corrections to vector-boson scattering in the standard model. Thereby also corrections of the electroweak interaction will be determined for the first time for this class of processes in a realistic setup. We have found that electroweak corrections change the predictions for vector-boson scattering at the LHC by several tens of per cent and are thus crucial for the correct description of the experimental data. We therefore plan to calculate these corrections for all relevant vector-boson scattering processes at the LHC. We will not only consider the genuine matrix elements for vector-boson scattering but include the complete set of tree-level and one-loop contributions in the full standard model that contribute to the relevant six-particle final states. In order to evaluate perturbative corrections to these complicated processes, appropriate methods have to be developed. Besides higher-order corrections in the standard model, we will also take into account effects from beyond thestandard model via appropriate effective couplings. If new physics pointing to specific extensions of the standard model should be observed at the LHC in the near future, our calculations can be adapted to the corresponding models.