Theoretical Particle Physics

Course with Participations of Group Members

Offers for Theses in the Group

One-jettiness soft function at NNLO in QCD

Computation of QCD corrections to LHC cross-sections usually requires to understand the structure of infra-red divergences. These obstructions appear both in so-called virtual and real corrections and require dedicated methods (e.g. “slicing methods”) to handle them and obtain finite expressions for numerical simulations. Infra-red divergences can be shown to factorise universally and the goal of the project is to analytically compute one of the ingredients which enter these general factorisation formulas, the so-called one-jettiness soft function. This function describes the contributions of soft radiation to cross sections at hadron colliders for processes with one jet and is an important ingredient for the jettiness slicing method. Technically, the computation of the required integrals can be tackled using advanced multi-loop techniques such as integration-by-parts and the method of differential equations.

suitable as

• Master’s Thesis Nuclear, Particle, and Astrophysics

Supervisor: Lorenzo Tancredi

Two-loop Feynman integrals for single top production at NNLO

Providing higher order QCD corrections to the hadronic production of top quarks at the LHC is an important step towards obtaining a more detailed understanding of electroweak symmetry breaking, due to the fact that top quarks receive their mass through interactions with the Higgs background field. Single top production is one of the most prominent top quark production channels at the LHC, with the t-channel process, which involves the production of a single top quark mediated by an exchange of a W boson, accounting for 70% of all single top quarks produced at LHC collisions. Recently, NNLO corrections to the so-called non-factorisable contributions to the single top t-channel were computed. The calculation was performed by calculating all the relevant 2-loop Feynman integrals numerically. It will be the aim of this project to provide an efficient analytic representation of these integrals in terms of special functions (e.g. multiple polylogarithms), by employing modern methods of multiloop calculations such as integration-by-part identities, canonical differential equations and the study of the relevant special functions.

suitable as

• Master’s Thesis Nuclear, Particle, and Astrophysics

Supervisor: Lorenzo Tancredi

Current and Finished Theses in the Group