Test of lepton flavour universality in W-boson decays into electrons and τ -leptons using pp collisions at s = 13 TeV with the ATLAS detector

Journal article

A measurement of the ratio of the branching fractions, Rτ/e = B(W → τν)/B(W → eν), is performed using a sample of W bosons originating from top-quark decays to final states containing τ-leptons or electrons. This measurement uses pp collisions at s = 13 TeV, collected by the ATLAS experiment at the Large Hadron Collider during Run 2, corresponding to an integrated luminosity of 140 fb−1. The W → τντ (with τ → eνeντ) and W → eνe decays are distinguished using the differences in the impact parameter distributions and transverse momentum spectra of the electrons. The measured ratio of branching fractions Rτ/e = 0.975 ± 0.012 (stat.) ± 0.020 (syst.), is consistent with the Standard Model assumption of lepton flavour universality in W-boson decays.

Authors: Aad, G; Aakvaag, E; Abbott, B; Abdelhameed, S; Abeling, K

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Springer
• Journal: Journal of High Energy Physics
• Volume: 2025
• Issue: 5
• Article number: 38
• Publication date: 2025-05-06
• Acceptance date: 2025-03-20
• DOI: 10.1007/jhep05(2025)038
• EISSN: 1029-8479
• ISSN: 1126-6708
• Language: English
• Keywords: Tau Physics; Hadron-Hadron Scattering; Flavour Physics