Electroweak corrections at very high energies for multi-particle processes

• Applicant: Professor Dr. Ansgar Denner
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 453656243

With the discovery of the Higgs boson at the Large Hadron Collider (LHC) in 2012, the last missing particle of the Standard Model (SM) of elementary particle physics has been established. Practically all processes studied at the LHC are well described by the SM, and thesearch for new physics did not yet yield any conclusive results so far. On the other hand, physics beyond the SM is required to explaindark matter and the matter-antimatter asymmetry of the universe. Therefore, the SM must be tested up to the highest possible energies and with highest possible precision.The theory community is working hard to provide sufficiently accurate predictions for collider processes. This requires to take into account perturbative corrections from the strong and the electroweak (EW) interaction. The importance of EW corrections grows if the energies of the observables are large compared to the masses of the EW gauge bosons. As a consequence, for many processes at the LHC, EW corrections reach several tens of per cent in high-energy tails of distributions, which are particularly sensitive to physicsbeyond the SM. At future colliders in the 100 TeV range, the EW corrections are so big that their resummation is mandatory.A framework that directly offers the resummation of leading logarithmic corrections is provided by Soft Collinear Effective Theory (SCET). SCET is an established tool to calculate and resum corrections of the strong interaction at low energies but also for processes at the LHC. Some years ago, a SCET formalism for scattering processes at high energies including EW corrections has been formulated. While it has been applied to some simple processes, it has so far neither been used for multi-particle processes nor implemented in Monte Carlo generators.The central goal of this research proposal is the establishment of a tool for the calculation of EW corrections for multi-particleprocesses at energies that are large compared to the EW scale. To this end, we will implement the SCET formalism into the Monte Carlo generator MoCaNLO. While several contributions can be taken from the literature, the most complicated one, the high-scale matching, has to be calculated for each process separately. We will use the matrix-element generator Recola2 and work out a corresponding model file to automatically calculate these contributions.In order to assess the accuracy of the SCET approach for EW corrections, we will compare corresponding results with those of complete next-to-leading-order calculations for different processes. Finally, we will calculate the resummed EW corrections for several hadronic processes in the 100-TeV energy range. Based on our results, an implementation of leading EW corrections into state-of-the-art Monte Carlo generators will be simplified.

• DFG Programme: Research Grants