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.

Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N.J., et al. (2025). Test of lepton flavour universality in W-boson decays into electrons and τ-leptons using pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector. JOURNAL OF HIGH ENERGY PHYSICS, 2025(5) [10.1007/jhep05(2025)038].

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

Di Micco, B.;Di Nardo, R.;Montereali, F.;Orestano, D.;
2025-01-01

Abstract

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.
2025
Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N.J., et al. (2025). Test of lepton flavour universality in W-boson decays into electrons and τ-leptons using pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector. JOURNAL OF HIGH ENERGY PHYSICS, 2025(5) [10.1007/jhep05(2025)038].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11590/524894
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