Author: Felix Richard Anger

Publisher:

Published: 2018

Total Pages:

ISBN-13:

Abstract: Precise theory predictions for scattering processes are an important input for the physics program at the Large Hadron Collider at CERN, Geneva. Notably the complex collider signatures of an electroweak vector boson and many jets that originate in either light partons (light jets) or bottom quarks (b jets) are relevant for both measurements of Standard Model processes as well as searches for new physics. In this thesis, we present new next-to-leading order QCD predictions for two related high-multiplicity processes at the LHC $\sqrt{s} = 13$ TeV. We show predictions for $Wb\bar{b}$ production in association with two and three light jets that we computed for the first time. In order to obtain the required one-loop amplitudes, we implement the numerical unitarity approach for massive particles in a new version of the BlackHat library. To this end, we devise and apply a new algorithm for the evaluation of D-dimensional unitarity cuts. It builds on a consistent embedding of external fermions states in dimensional regularization and reduces the computational complexity of our calculations. Furthermore, we present next-to-leading order QCD predictions for $V+n$-jet production in association with up to $n = 5$ light jets for $V = W^\pm$ and with up to $n = 4$ light jets for $V = Z$, which we extend to the higher center-of-mass energy of the Large Hadron Collider Run-II. For these processes we compare results obtained with fixed-order scales such as $\hat{H}_T^'/2$ with the MiNLO reweighting procedure