Aad, G.Abbott, B.Abbott, D.C.Abed Abud, A.Abeling, K.Abhayasinghe, D.K.Ike2026-04-042026-04-0420251748-0221https://doi.org/10.1088/1748-0221/20/02/P02018https://hdl.handle.net/11411/10220The high-luminosity phase of LHC operations (HL-LHC), will feature a large increase in simultaneous proton-proton interactions per bunch crossing up to 200, compared with a typical leveling target of 64 in Run 3. Such an increase will create a very challenging environment in which to perform charged particle trajectory reconstruction, a task crucial for the success of the ATLAS physics program, and will exceed the capabilities of the current ATLAS Inner Detector (ID). A new all-silicon Inner Tracker (ITk) will replace the current ID in time for the start of the HL-LHC. To ensure successful use of the ITk capabilities in Run 4 and beyond, the ATLAS tracking software has been successfully adapted to achieve state-of-the-art track reconstruction in challenging high-luminosity conditions with the ITk detector. This paper presents the expected tracking performance of the ATLAS ITk based on the latest available developments since the ITk technical design reports. © 2025 CERN for the benefit of the ATLAS collaboration.eninfo:eu-repo/semantics/openAccessCalibrationCluster FindingFitting MethodsGaseous Imaging And Tracking DetectorsParticle Tracking Detectors (Solid-State Detectors)Pattern RecognitionVertexing AlgorithmsArticle2-s2.0-10500120799510.1088/1748-0221/20/02/P020182Q220