Electroweak pp → W^±W^±jj production and its experimental challenges

The measurements of the electroweak sector of the Standard Model are one way to probe the mechanism of electroweak symmetry breaking (EWSB) at the LHC. In this context, the scattering of vector bosons is a key process. In particular, the scattering amplitude of the production of a pair of W bosons increases with energy, violating unitarity, while the exchange of Z/γ* and Higgs bosons should cancel these divergences. The cancellations are exact if the vector bosons self-couplings and their couplings to the Higgs boson have the values predicted by the Standard Model. Deviations from these predictions would lead to changes in the production rate as a function of invariant diboson mass. Therefore, W boson scattering provides a crucial test of EWSB and constrain possible contributions from new physics. In this talk an analysis of electroweak pp → W^±W^±jj production is presented, in the final signature of two leptons with the same electric charge, missing transverse energy and two jets, within the ATLAS experiment at LHC. The final state of two leptons with the same charge is chosen to suppress contributions from WW production accompanied by jets from initial state radiation, but is experimentally more challenging due to the contributions from the opposite-sign di-lepton production, where the charge of one electron is wrongly reconstructed. This experimental issue is clarified, and ways to measure or reduce its contributions in the context of this analysis are presented.