Processes with τ-leptons in the final state are important for Standard Model measurements and searches for physics beyond the Standard Model. The ATLAS experiment at the Large Hadron Collider observes τ-leptons produced in proton–proton collisions only through their decay products. Data analyses involving hadronically decaying τ-leptons face challenges due to backgrounds from jets misidentified as τ-leptons that are not modelled reliably by Monte Carlo simulations. Data-driven methods such as the fake-factor method allow such misidentified backgrounds to be predicted by measuring transfer factors, known as fake factors, in data from dedicated regions. This paper describes a refined technique for determining the fake factors, the Universal Fake Factor method. It evaluates the fake factors for a signal region by using fake factors from samples enriched in different sources of jets misidentified as τ-leptons (light-quark, gluon, b-quark, and pile-up jets). Each fake factor is calculated as a linear combination of fake factors measured in these different enriched samples. For the full Run 2 data set, the systematic uncertainty of the calculated fake factors, evaluated using W(μν) enriched event sample, ranges from 15 to 35% depending on the τ-lepton’s transverse momentum and charged-particle decay multiplicity.

Null, N., Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., et al. (2025). Estimation of backgrounds from jets misidentified as τ -leptons using the Universal Fake Factor method with the ATLAS detector. EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 85(12), 1441-1-1441-36 [10.1140/epjc/s10052-025-14916-1].

Estimation of backgrounds from jets misidentified as τ -leptons using the Universal Fake Factor method with the ATLAS detector

Alberghi, G. L.;Alfonsi, F.;Ballabene, E.;Bellagamba, L.;Bianco, G.;Boscherini, D.;Bruni, A.;Carratta, G.;Cremonini, D.;De Castro, S.;Fabbri, F.;Fabbri, L.;Franchini, M.;Gabrielli, A.;Giacobbe, B.;Lasagni Manghi, F.;Levrini, G.;Nechaeva, S.;Polini, A.;Rinaldi, L.;Romano, M.;Sanzani, E.;Sbarra, C.;Sbrizzi, A.;Semprini-Cesari, N.;Sioli, M.;Todome, K.;Valentinetti, S.;Villa, M.;Vittori, C.;Vivarelli, I.;Zoccoli, A.;
2025

Abstract

Processes with τ-leptons in the final state are important for Standard Model measurements and searches for physics beyond the Standard Model. The ATLAS experiment at the Large Hadron Collider observes τ-leptons produced in proton–proton collisions only through their decay products. Data analyses involving hadronically decaying τ-leptons face challenges due to backgrounds from jets misidentified as τ-leptons that are not modelled reliably by Monte Carlo simulations. Data-driven methods such as the fake-factor method allow such misidentified backgrounds to be predicted by measuring transfer factors, known as fake factors, in data from dedicated regions. This paper describes a refined technique for determining the fake factors, the Universal Fake Factor method. It evaluates the fake factors for a signal region by using fake factors from samples enriched in different sources of jets misidentified as τ-leptons (light-quark, gluon, b-quark, and pile-up jets). Each fake factor is calculated as a linear combination of fake factors measured in these different enriched samples. For the full Run 2 data set, the systematic uncertainty of the calculated fake factors, evaluated using W(μν) enriched event sample, ranges from 15 to 35% depending on the τ-lepton’s transverse momentum and charged-particle decay multiplicity.
2025
Null, N., Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., et al. (2025). Estimation of backgrounds from jets misidentified as τ -leptons using the Universal Fake Factor method with the ATLAS detector. EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 85(12), 1441-1-1441-36 [10.1140/epjc/s10052-025-14916-1].
Null, Null; Aad, G.; Aakvaag, E.; Abbott, B.; Abdelhameed, S.; Abeling, K.; Abicht, N. J.; Abidi, S. H.; Aboelela, M.; Aboulhorma, A.; Abramowicz, H.;...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/1045573
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