Anomalous quartic gauge couplings and unitarization for the vector boson scattering process $pp\rightarrow W^+W^+jjX\rightarrow \ell^+\nu_\ell\ell^+\nu_\ell jjX$

TL;DR

This paper develops a numerical unitarization scheme for vector boson scattering at the LHC, enabling more accurate analysis of potential new physics effects in quartic gauge couplings within an effective field theory framework.

Contribution

It introduces a novel unitarization method for off-shell VBS processes and implements it in VBFNLO, improving phenomenological studies of quartic gauge couplings.

Findings

Unitarization scheme successfully applied to same-sign W scattering.

Distributions can distinguish effects of higher-dimensional operators.

Method includes leptonic decays and NLO QCD corrections.

Abstract

Weak vector boson scattering (VBS) at the LHC provides an excellent source of information on the structure of quartic gauge couplings and possible effects of physics beyond the SM in electroweak symmetry breaking. Parameterizing deviations from the SM within an effective field theory at tree level, the dimension-8 operators, which are needed for sufficiently general modeling, lead to unphysical enhancements of cross sections within the accessible energy range of the LHC. Preservation of unitarity limits is needed for phenomenological studies of the $VVjj$ events which signify VBS. Here we develop a numerical unitarization scheme for the full off-shell VBS processes and apply it to same-sign $W$ scattering, i.e. processes like $qq\to qqW^+W^+$. The scheme is implemented within the Monte Carlo program VBFNLO, including leptonic decay of the weak bosons and NLO QCD corrections. Distributions differentiating between higher dimensional operators are discussed.