Performance of the reconstruction of large impact parameter tracks in the inner detector of ATLAS

Searches for long-lived particles (LLPs) are among the most promising avenuesfor discovering physics beyond the Standard Model at the Large Hadron Collider(LHC). However, displaced signatures are notoriously difficult to identify dueto their ability to evade standard object reconstruction strategies. Inparticular, the default ATLAS track reconstruction applies strict pointingrequirements which limit sensitivity to charged particles originating far fromthe primary interaction point. To recover efficiency for LLPs decaying withinthe tracking detector volume, the ATLAS Collaboration employs a dedicatedlarge-radius tracking (LRT) pass with loosened pointing requirements. DuringRun 2 of the LHC, the LRT implementation produced many incorrectlyreconstructed tracks and was therefore only deployed in small subsets ofevents. In preparation for LHC Run 3, ATLAS has significantly improved bothstandard and large-radius track reconstruction performance, allowing for LRT torun in all events. This development greatly expands the potential phase-spaceof LLP searches and streamlines LLP analysis workflows. This paper willhighlight the above achievement and report on the readiness of the ATLASdetector for track-based LLP searches in Run 3.