Impact of an Extended ATLAS Tracker on $W^{\pm}W^{\pm}$ Scattering at a High-Luminosity LHC

The ATLAS detector will undergo a major upgrade in Phase-II in order to maintain the high performance in the challenging environmental conditions that will be imposed by the High-Luminosity (HL) LHC. Several inner detector scenarios are under consideration including an extension of the nominal tracker from $|\eta| < 2.7$ up to $|\eta| < 3.2$ (medium tracker) or $|\eta| < 4.0$ (extended tracker). In this analysis the impact of the different scenarios of the upgraded ATLAS Tracker (ITk) on the $W^{\pm}W^{\pm}$ scattering in the $l^{\pm}\nu l^{\pm} \nu jj$ final state at a HL-LHC is evaluated. The outcome emphasizes the importance of the suppression of forward jets caused by high pile-up of up to $<\mu> = 200$. The study shows a significant improvement for the tracker layouts with a larger $\eta$ coverage than the nominal one. Hence, the physics process studied provides a strong argument for the extension of the $\eta$ coverage of the ITk.