Dr Alexander Karlberg

Abstract:

Theoretical predictions with next-to-next-to-leading order (NNLO) QCD accuracy combined with the next-to-leading order (NLO) electroweak (EW) corrections are presented for differential observables of the double-Higgs production process via vector-boson fusion. While the QCD corrections were previously known, the EW ones are computed here for the first time. The numerical results are obtained for a realistic experimental set-up at the LHC and are presented in the form of fiducial cross sections and differential distributions. Within this setup we find that the VBF approximation employed in the NNLO QCD correction is accurate at the sub-percent level. We find that the NLO EW corrections within the fiducial volume are - 6.1 % , making them of almost the same order as the NLO QCD corrections. In some kinematic regions they can grow as large as - 30 % making them the dominant radiative corrections. When the EW corrections are combined with the NNLO QCD corrections we find a total correction of - 14.8 % . The results presented here thus comprise the state-of-the-art theoretical predicition for the double-Higgs production via vector-boson fusion, which will be of value to the high-luminosity programme at the LHC.

Abstract:

We calculate the fully differential next-to-next-to-leading order (NNLO) QCD corrections to vector-boson fusion (VBF) Higgs pair production. This calculation is achieved in the limit in which there is no colored cross-talk between the colliding protons, using the projection-to-Born method. We present differential cross sections of key observables, showing corrections of up to 3%–4% at this order after typical VBF cuts, with the total cross section receiving contributions of about 2%. In contrast to single Higgs VBF production, we find that the NNLO corrections are for the most part within the next-to-leading order scale uncertainty bands.

Abstract:

© 2019, The Author(s). We present an implementation of WZjj production via vector-boson fusion in the POWHEG BOX, a public tool for the matching of next-to-leading order QCD calculations with multi-purpose parton-shower generators. We provide phenomenological results for electroweak WZjj production with fully leptonic decays at the LHC in realistic setups and discuss theoretical uncertainties associated with the simulation. We find that beyond the leading-order approximation the dependence on the unphysical factorization and renormalization scales is mild. The two tagging jets are furthermore very stable against parton-shower effects. However, considerable sensitivities to the shower Monte-Carlo program used are observed for central-jet veto observables.

Abstract:

We calculate the next-to-next-to-next-to-leading order (N$^3$LO) QCD corrections to vector-boson fusion (VBF) Higgs pair production in the limit in which there is no partonic exchange between the two protons. We show that the inclusive cross section receives negligible corrections at this order, while the scale variation uncertainties are reduced by a factor four. We present differential distributions for the transverse momentum and rapidity of the final state Higgs bosons, and show that there is almost no kinematic dependence to the third order corrections. Finally we study the impact of deviations from the Standard Model in the trilinear Higgs coupling, and show that the structure of the higher order corrections does not depend on the self-coupling. These results are implemented in the latest release of the proVBFH-incl program.

Abstract:

This document summarises the talks and discussions happened during the VBSCan Split17 workshop, the first general meeting of the VBSCan COST Action network. This collaboration is aiming at a consistent and coordinated study of vector-boson scattering from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.