Configuration and performance of the ATLAS b-jet triggers in Run 2

Journal article

Abstract Several improvements to the ATLAS triggers used to identify jets containing b -hadrons ( b -jets) were implemented for data-taking during Run 2 of the Large Hadron Collider from 2016 to 2018. These changes include reconfiguring the b -jet trigger software to improve primary-vertex finding and allow more stable running in conditions with high pile-up, and the implementation of the functionality needed to run sophisticated taggers used by the offline reconstruction in an online environment. These improvements yielded an order of magnitude better light-flavour jet rejection for the same b -jet identification efficiency compared to the performance in Run 1 (2011–2012). The efficiency to identify b -jets in the trigger, and the conditional efficiency for b -jets that satisfy offline b -tagging requirements to pass the trigger are also measured. Correction factors are derived to calibrate the b -tagging efficiency in simulation to match that observed in data. The associated systematic uncertainties are substantially smaller than in previous measurements. In addition, b -jet triggers were operated for the first time during heavy-ion data-taking, using dedicated triggers that were developed to identify semileptonic b -hadron decays by selecting events with geometrically overlapping muons and jets.

Authors: Aad, G; Abbott, B; Abbott, DC; Abed Abud, A; Abeling, K

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: SpringerOpen
• Journal: The European Physical Journal C
• Volume: 81
• Issue: 12
• Pages: 1087
• Article number: 1087
• Publication date: 2021-12-09
• DOI: 10.1140/epjc/s10052-021-09775-5
• EISSN: 1434-6052
• ISSN: 1434-6044
• Language: English
• Keywords: Physics; Particle physics; Large Hadron Collider; Computer science; Jet (fluid); Atlas (anatomy); Theoretical computer science; Vertex (graph theory); Hadron; Mechanics; Nuclear physics