Browsing by Author "Borshch, V."

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Development of Systematic Uncertainty-Aware Neural Network Trainings for Binned-Likelihood Analyses at the LHC
(Springer Nature, 2025) Druzhkin, D.; Borshch, V.; Babaev, A.; Uzunian, A.; Slabospitskii, S.; Kachanov, V.; Tchekhovski, V.
We propose a neural network training method capable of accounting for the effects of systematic variations of the data model in the training process and describe its extension towards neural network multiclass classification. The procedure is evaluated on the realistic case of the measurement of Higgs boson production via gluon fusion and vector boson fusion in the ττ decay channel at the CMS experiment. The neural network output functions are used to infer the signal strengths for inclusive production of Higgs bosons as well as for their production via gluon fusion and vector boson fusion. We observe improvements of 12 and 16% in the uncertainty in the signal strengths for gluon and vector-boson fusion, respectively, compared with a conventional neural network training based on cross-entropy. © CERN for the benefit of the CMS Collaboration 2025.
Citation - Scopus: 1
Search for Pair Production of Heavy Particles Decaying to a Top Quark and a Gluon in the Lepton+Jets Final State in Proton–Proton Collisions at √s=13 TeV
(Springer Nature, 2025) Druzhkin, Dmitry; Borshch, V.; Babaev, A. A.; Uzunian, A. V.; Slabospitskii, S.; Konstantinov, Dmitri A.; Kozyrev, A. N.
A search is presented for the pair production of new heavy resonances, each decaying into a top quark (t) or antiquark and a gluon (g). The analysis uses data recorded with the CMS detector from proton–proton collisions at a center-of-mass energy of 13TeV at the LHC, corresponding to an integrated luminosity of 138fb-1. Events with one muon or electron, multiple jets, and missing transverse momentum are selected. After using a deep neural network to enrich the data sample with signal-like events, distributions in the scalar sum of the transverse momenta of all reconstructed objects are analyzed in the search for a signal. No significant deviations from the standard model prediction are found. Upper limits at 95% confidence level are set on the product of cross section and branching fraction squared for the pair production of excited top quarks in the t∗→tg decay channel. The upper limits range from 120 to 0.8fb for a t∗with spin-1/2 and from 15 to 1.0fb for a t∗with spin-3/2. These correspond to mass exclusion limits up to 1050 and 1700GeV for spin-1/2 and spin-3/2 t∗particles, respectively. These are the most stringent limits to date on the existence of t∗→tg resonances. © 2025 Elsevier B.V., All rights reserved.