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Torsten ÅKESSON

Torsten Åkesson

Professor Emeritus / Expert

Torsten ÅKESSON

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

Author

  • G. Aad
  • T.P.A. Åkesson
  • K.S.V. Astrand
  • C. Doglioni
  • P.A. Ekman
  • V. Hedberg
  • H. Herde
  • B. Konya
  • E. Lytken
  • R. Poettgen
  • O. Smirnova
  • E.J. Wallin
  • L. Zwalinski
Show all

Summary, in English

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. © CERN for the benefit of the ATLAS Collaboration 2025.

Department/s

  • Particle and nuclear physics
  • eSSENCE: The e-Science Collaboration
  • Department of Physics

Publishing year

2025

Language

English

Publication/Series

European Physical Journal C

Volume

85

Issue

12

Document type

Journal article

Publisher

Springer Nature

Topic

  • Subatomic Physics

Keywords

  • Bosons
  • Charged particles
  • Colliding beam accelerators
  • Fighter aircraft
  • Microstrip devices
  • Monte Carlo methods
  • ATLAS detectors
  • ATLAS experiment
  • Factor methods
  • Final state
  • Large Hadron Collider
  • Large-hadron colliders
  • Model measurements
  • Model search
  • Standard model
  • The standard model
  • Intelligent systems
  • Piles

Status

Published

ISBN/ISSN/Other

  • ISSN: 1434-6044