CMS-PAS-BTV-25-002

CMS-PAS-BTV-25-002
Performance of heavy-flavour jet identification in the CMS high-level trigger during LHC Run 3
CMS Collaboration
2026-05-14

Abstract: The CMS trigger system plays a crucial role during data taking, reducing the large collision rate delivered by the Large Hadron Collider (LHC) to a few kHz for data storage and subsequent offline analysis. The system aims to maintain high selection efficiency for processes involving jets from heavy-flavour quarks (b and c), which constitute a distinctive signature in many physics analyses. To achieve this while maintaining a sustainable trigger output rate, dedicated jet flavour identification methods are developed and optimized for use in the CMS High Level Trigger (HLT). This note presents the design, commissioning, and performance of deep-learning-based jet identification algorithms deployed in the HLT during LHC Run 3, which delivered proton-proton collisions at $ \sqrt{s}= $ 13.6 TeV. The new algorithms enabled significant improvements in signal efficiency for a variety of key physics processes, including the non-resonant production of Higgs boson pairs decaying to four b quarks as well as Higgs boson production via both vector boson fusion and in association with a $ \mathrm{t\bar{t}} $ pair, in the $ \mathrm{H}\rightarrow\mathrm{b\bar{b}} $ and $ \mathrm{H}\rightarrow\mathrm{c\bar{c}} $ decay channels.
Links: CDS record (PDF) ; CADI line (restricted) ; These preliminary results are superseded in this paper, Submitted to JHEP. The superseded preliminary plots can be found here.

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