Isolating Unisolated Upsilons with Anomaly Detection in CMS Open Data

Abstract

We present the first study of anti-isolated Upsilon decays to two muons (${\rm Y}\to {\mu }^{+}{\mu }^{-}$) in proton-proton collisions at the Large Hadron Collider. Using a machine learning (ML)-based anomaly detection strategy, we "rediscover" the ${\rm Y}$ in 13 TeV CMS Open Data from 2016, despite overwhelming anti-isolated backgrounds. We elevate the signal significance to $6.4\sigma$ using these methods, starting from $1.6\sigma$ using the dimuon mass spectrum alone. Moreover, we demonstrate improved sensitivity from using an ML-based estimate of the multi-feature likelihood compared to traditional "cut-and-count" methods. Our work demonstrates that it is possible and practical to find real signals in experimental collider data using ML-based anomaly detection, and we distill a readily-accessible benchmark dataset from the CMS Open Data to facilitate future anomaly detection developments.

5+3 pages, 4 figures; v2: minor changes. Code available at https://github.com/hep-lbdl/dimuonAD/

References in corpus (24)

• XGBoost: A Scalable Tree Boosting System
• Asymptotic formulae for likelihood-based tests of new physics
• Normalizing Flows: An Introduction and Review of Current Methods
• Heavy-flavour and quarkonium production in the LHC era: from proton-proton to heavy-ion collisions
• Performance of the CMS muon detector and muon reconstruction with proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Classification without labels: Learning from mixed samples in high energy physics
• Anomaly Detection for Resonant New Physics with Machine Learning
• Extending the Bump Hunt with Machine Learning
• Dijet resonance search with weak supervision using $\sqrt{s}=13$ TeV $pp$ collisions in the ATLAS detector
• The Dark Machines Anomaly Score Challenge: Benchmark Data and Model Independent Event Classification for the Large Hadron Collider
• Classifying Anomalies THrough Outer Density Estimation (CATHODE)
• Dark Force Detection in Low Energy e-p Collisions
• Study of $J/\psi$ production in jets
• NRQCD Confronts LHCb Data on Quarkonium Production within Jets
• A search for pair production of new light bosons decaying into muons in proton-proton collisions at 13 TeV
• Diffractive semi-hard production of a $J/\psi$ or a ${\rm Y}$ from single-parton fragmentation plus a jet in hybrid factorization
• Analytic and Monte Carlo Studies of Jets with Heavy Mesons and Quarkonia
• Search for new phenomena in two-body invariant mass distributions using unsupervised machine learning for anomaly detection at $\sqrt{s}=13$ TeV with the ATLAS detector
• Statistics of weighted Poisson events and its applications
• Anomaly detection search for new resonances decaying into a Higgs boson and a generic new particle $X$ in hadronic final states using $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector
• Model-agnostic search for dijet resonances with anomalous jet substructure in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Searching in CMS Open Data for Dimuon Resonances with Substantial Transverse Momentum
• Fragmentation of jets containing a prompt J$/\psi$ meson in PbPb and pp collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV
• Realistic constraints on the doubly charged bilepton couplings from Bhabha scattering with LEP data

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