Studies on polarization in the scattering of two vector bosons with the ATLAS experiment at the LHC

The scattering of two vector bosons is a process well suited for studying the mechanism of electroweak symmetry breaking. Without a Higgs boson or an equivalent mechanism the predicted cross section for the scattering of longitudinally polarized bosons violates unitarity at high energies. A precise measurement of the cross section of this process could eventually help us to understand if the observed Higgs boson behaves like a Standard Model one or might give us hints at new physics beyond the Standard Model. This work investigates how the polarization of the vector bosons can be extracted from the decay products measured with the ATLAS detector. To do this two methods of generating simulations of polarized bosons are studied. It will be shown that the approach of using the narrow-width-approximation is superior to the reweighting method used so far in ATLAS publications. Lastly the sensitivity of kinematic variables to the polarization of the bosons is investigated. For the 𝑍 boson these are the Cosine of the decay angle as well as variables related to the reconstructed particle. The 𝑊’s polarization can be best measured with observables of its lepton as well as the missing transverse momentum. The balance of the jets transverse momenta is even sensitive to the combination of both bosons.