Expected performance for an upgraded ATLAS detector at High-Luminosity LHC

This note summarises the expected performance of the ATLAS detector after the upgrades for the High-Luminosity LHC. The performance evaluations are based on full simulation of the upgraded Phase-II detector with in-time and out-of-time pile-up for luminosities up to $7.5\times10^{34}$ cm$^{-2}$ s$^{-1}$ corresponding to an average of number of inelastic collisions per bunch crossing of up to 200. The simulation uses an updated and optimised design of the inner tracker upgrade and an improved reconstruction software, resulting in improved performance compared to previous studies for High-Luminosity LHC.