Electroweak corrections at very high energies for multi-particle processes
Final Report Abstract
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 the search for new physics did not yield any conclusive results so far. On the other hand, physics beyond the SM is required to explain experimental facts like the observation of dark matter and the matter–antimatter asymmetry of the universe. The strategy of the particlephysics community is thus to search for new phenomena and test the SM up to the highest possible energies and with highest possible precision. The theoretical particle physics community is working hard to provide sufficiently accurate predictions for collider processes. This requires to take into account perturbative corrections from the strong but also from the electroweak (EW) interaction. The importance of EW corrections grows if the energies of the studied 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 a percent in high-energy tails of distributions, which are particularly sensitive to physics beyond the SM. At future colliders in the 100 TeV range, the EW corrections are so big that their resummation is mandatory. A perturbative framework that naturally offers the resummation of logarithmically enhanced 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 high-energy 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 immediately applied to some simple LHC 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 was the establishment of a tool for the reliable calculation of EW corrections to multi-particle processes at energies that are large compared to the EW scale. To this end, the SCET framework for EW corrections was implemented into the Monte Carlo integrator MoCaNLO. In order to calculate the process-dependent highscale matching contributions, a suitable model file for the matrix element generator Recola2 was implemented. With the constructed tool, we evaluated the EW corrections for massive diboson production at future hadron and lepton colliders. We studied the accuracy of the SCET results by comparing to an exact next-to-leading-order calculation and the effects of resummation within SCET. Our results provide important inputs for the implementation of EW corrections into state-of-the-art Monte Carlo generators and estimates for the accuracy to be expected from such a formalism.
