A2b: Multi-boson physics at the LHC

This project aims at a better description of processes involving multiple vector bosons at the LHC, in particular vector-boson scattering and multi-boson s-channel production. It will include next-to-leading order QCD and electroweak corrections, as well as the modelling of realistic final states with an efficient Monte Carlo event generator. The project also involves the implementation of higher-dimensional operators in an effective field theory framework, and subsequent phenomenological studies of the sensitivity of such processes to BSM effects. To achieve this goal, substantial technical advances need to be made, both on the loop amplitude representation as well as on the phase space sampling side. Modern machine learning methods will be explored to push the efficiency of such a Monte Carlo framework to a higher level.

1. Vector-boson scattering:
   • study all charged and neutral bosons (+ photon, + Higgs);
   • compare and combine analytical and numerical methods;
   • match to D=6 ⊕ D=8 low energy effective operators coherently; signal vs background separation for future LHC run;
2. Predictions and limits for $q \bar q \to n$~bosons ($n > 2$):
   • disentangle and relate final states in $q \bar q \to VVV$ and $VVVV$;
   • visible and invisible new physics as inelastic scattering;
3. Combine predictions and apply to incoming LHC results:
   • unitarity relations apply to all multi-boson processes coherently;
   • complete simulations and tools for meaningful data analysis;
   • implications for effective theory and (simplified) models;
   • model-independent interpretation and sensitivity to Higgs potential.