Minimising Event Size, Maximising Physics: Inclusive Particle Isolation for LHCb's Run 3

Abstract

The Run 3 of the LHC brings unprecedented luminosity and a surge in data volume to the LHCb detector, necessitating a critical reduction in the size of each reconstructed event without compromising the physics reach of the heavy-flavour programme. While signal decays typically involve just a few charged particles, a single proton-proton collision produces hundreds of tracks, with charged particle information dominating the event size. To address this imbalance, a suite of inclusive isolation tools have been developed, including both classical methods and a novel Inclusive Multivariate Isolation (IMI) algorithm. The IMI unifies the key strengths of classical isolation techniques and is designed to robustly handle diverse decay topologies and kinematics, enabling efficient reconstruction of decay chains with varying final-state multiplicities. It consistently outperforms traditional methods, with superior background rejection and high signal efficiency across diverse channels and event multiplicities. By retaining only the most relevant particles in each event, the method achieves a 45 % reduction in data size while preserving full physics performance, selecting signal particles with 99% efficiency. We also validate IMI on Run 3 data, confirming its robustness under real data-taking conditions. In the long term, IMI could provide a fast, lightweight front-end to support more compute-intensive selection strategies in the high-multiplicity environment of the High-Luminosity LHC.

Published in EPJ C

References in corpus (24)

• XGBoost: A Scalable Tree Boosting System
• LHCb Detector Performance
• Study of the rare decays of $B_s^0$ and $B^0$ mesons into muon pairs using data collected during 2015 and 2016 with the ATLAS detector
• Measurement of the Inclusive Jet Cross Section at the Fermilab Tevatron p-pbar Collider Using a Cone-Based Jet Algorithm
• Determination of the quark coupling strength $|V_{ub}|$ using baryonic decays
• Tesla : an application for real-time data analysis in High Energy Physics
• Allen: A high level trigger on GPUs for LHCb
• Measurement of the B${}_{\mathrm{S}}^0$ $\to$ ${\mu }^{+}{\mu }^{-}$ decay properties and search for the B${}^0$ $\to$ ${\mu }^{+}{\mu }^{-}$ decay in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Search for the decay Bs0 -> mu mu with the ATLAS detector
• The LHCb upgrade I
• Opposite-side flavour tagging of B mesons at the LHCb experiment
• Measurement of the ratios of branching fractions $\mathcal{R}(D^{\ast })$ and $\mathcal{R}(D^0)$
• Test of lepton flavour universality using $B^0\to D^{\ast -}{\tau }^{+}{\nu }_{\tau }$ decays with hadronic $\tau$ channels
• Search for B(s) and B to dimuon decays in pp collisions at 7 TeV
• A comprehensive real-time analysis model at the LHCb experiment
• A precise measurement of the $B^0$ meson oscillation frequency
• Search for Bs --> mu+ mu- at D0
• Precision measurement of forward $Z$ boson production in proton-proton collisions at $\sqrt{s}=13$ TeV
• Search for $B_s\to {\mu }^{+}{\mu }^{-}$ and $B_d\to {\mu }^{+}{\mu }^{-}$ decays with the full CDF Run II data set
• Measurement of the relative $B^{-}\to D^0/D^{\ast 0}/D^{\ast \ast 0}{\mu }^{-}{\overline{\nu }}_{\mu }$ branching fractions using $B^{-}$ mesons from $\overline{B}{}_{s2}^{\ast 0}$ decays
• Identification of charm jets at LHCb
• The LHCb Sprucing and Analysis Productions
• FunTuple: A new N-tuple component for offline data processing at the LHCb experiment
• Scalable Multi-Task Learning for Particle Collision Event Reconstruction with Heterogeneous Graph Neural Networks