An alternative subtraction scheme using Nagy-Soper dipoles

In this thesis we address an alternative subtraction scheme in high energy colliders at Next-to-Leading Order (NLO) QCD calculations. In particular, we focus on the treatment of real radiation contributions in the soft and collinear limits. After UV-renormalization, the remaining infrared singularities appearing both in the real radiation and in the virtual contributions can be regularized using dipole subtraction method. In this scheme, dipoles are based on the momentum mapping and on the splitting functions derived from an improved parton shower formulation with quantum interference effects. In our new scheme, we employ a slightly altered momentum mapping such that the number of subtraction terms is greatly reduced in comparison with the standard Catani-Seymour scheme. In addition, the new scheme also facilitates the matching of NLO calculations with parton showers using the same splitting functions. We also achieve the complete integrations of the splitting functions over an unresolved one parton phase space, obtaining the correct soft and collinear singularity structures that are necessary to cancel the soft divergences in the virtual contributions. We discuss the general framework setup of the scheme as well as some scattering processes at colliders; we find complete agreement with the results in the widely used Catani-Seymour dipole subtraction scheme