Measurement of the top-quark pole mass in dileptonic tt¯ + 1-jet events at √s = 13 TeV with the ATLAS experiment

Summary, in English

A measurement of the top-quark pole mass mtpole is presented in tt¯ events with an additional jet, tt¯ + 1-jet, produced in pp collisions at s=13 TeV. The data sample, recorded with the ATLAS experiment during Run 2 of the LHC, corresponds to an integrated luminosity of 140 fb−1. Events with one electron and one muon of opposite electric charge in the final state are selected to measure the tt¯ + 1-jet differential cross-section as a function of the inverse of the invariant mass of the tt¯ + 1-jet system. Iterative Bayesian Unfolding is used to correct the data to enable comparison with fixed-order calculations at next-to-leading-order accuracy in the strong coupling. The process pp→tt¯j2→3, where top quarks are taken as stable particles, and the process pp→bb¯l+νl−ν¯j2→7, which includes top-quark decays to the dilepton final state and off-shell effects, are considered. The top-quark mass is extracted using a χ2 fit of the unfolded normalized differential cross-section distribution. The results obtained with the 2 → 3 and 2 → 7 calculations are compatible within theoretical uncertainties, providing an important consistency check. The more precise determination is obtained for the 2 → 3 measurement: mtpole=170.7±0.3stat.±1.4syst.±0.3scale±0.2PDF⊕αS GeV, which is in good agreement with other top-quark mass results. © The Author(s) 2025.

• Author: G. Aad; T.P.A. Åkesson; K.S.V. Astrand; L. Calic; C. Doglioni; P.A. Ekman; V. Hedberg; H. Herde; B. Konya; E. Lytken; R. Poettgen; O. Smirnova; N. Sur; E.J. Wallin; L. Zwalinski
• Department/s: Particle and nuclear physics; eSSENCE: The e-Science Collaboration; Department of Physics
• Publishing year: 2025
• Language: English
• Publication/Series: Journal of High Energy Physics
• Volume: 2025
• Issue: 12
• Links: http://dx.doi.org/10.1007/JHEP12(2025)023
• Document type: Journal article
• Publisher: Springer
• Topic: Subatomic Physics
• Keywords: Hadron-Hadron Scattering; Top Physics
• Status: Published
• ISBN/ISSN/Other: ISSN: 1029-8479