Expected $b$-tagging performance with the upgraded ATLAS Inner Tracker detector at the High-Luminosity LHC

In view of the operation of the ATLAS detector under High-Luminosity LHC conditions, the central tracking system will be upgraded to maintain high levels of performance with a peak instantaneous luminosity of $7.5\times10^{34}~\mathrm{cm}^{-2}s^{-1}$, corresponding to an average of about 200 inelastic proton-proton collisions per beam-crossing. The new Inner Tracker (ITk), with an extended pseudo-rapidity coverage up to $|\eta|$=4, is planned to operate for more than ten years, during which time the LHC aims to deliver $4~\mathrm{ab}^{-1}$ of integrated luminosity. The algorithms used for the identification of the hadronic jets stemming from $b$-quarks rely heavily on track reconstruction, and their performance is therefore strongly dependent on the design of this detector. This document presents the $b$-tagging performance expected with the latest ITk design, updated since the ITk Pixel Detector Technical Design Report.