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Compact Muon Solenoid
LHC, CERN

CMS-PAS-TAU-24-001
Identification of tau leptons using a convolutional neural network with domain adaptation in the CMS experiment
Abstract: The DeepTau identification algorithm, based on deep neural network techniques, has been developed to reduce the fraction of jets, muons, and electrons misidentified as hadronically decaying tau leptons ($ \tau_\mathrm{h} $) in the CMS experiment. The latest version of this algorithm includes domain adaptation by backpropagation, a technique that reduces data-to-simulation discrepancies in the region with the highest purity of genuine $ \tau_\mathrm{h} $ candidates. Additionally, a refined training workflow improves classification performance, with a reduction of 30-50% in the probability for jets to be misidentified as a $ \tau_\mathrm{h} $ for a given reconstruction and identification efficiency. This note presents the main novelties introduced to the DeepTau algorithm and evaluates its performance in LHC proton-proton collision data at $ \sqrt{s}= $ 13 and 13.6 TeV collected in 2018 and 2022, respectively, with integrated luminosities of 60 and 35 fb$ ^{-1} $. The techniques to determine data-to-simulation scale factors are presented with a subset of results among the ones deployed centrally for CMS physics analyses. This document has been revised with respect to the version dated May 2, 2025.
CMS Publications
Compact Muon Solenoid
LHC, CERN