Searches for lepton-flavour-violating decays of the Higgs boson into eτ and μτ in √s=13 TeV pp collisions with the ATLAS detector

Beck, H.P.; Chatterjee, M.; Franconi, L.; Halser, L.; Haug, S.; Ilg, A.; Müller, R.; O'Neill, A.P.; Schefer, M.M.; Weber, M.S. (2023). Searches for lepton-flavour-violating decays of the Higgs boson into eτ and μτ in √s=13 TeV pp collisions with the ATLAS detector. Journal of High Energy Physics, 2023(7) Springer 10.1007/JHEP07(2023)166

JHEP07_2023_166.pdf - Published Version
Available under License Creative Commons: Attribution (CC-BY).

Download (3MB) | Preview

This paper presents direct searches for lepton flavour violation in Higgs boson decays, H → eτ and H → μτ, performed using data collected with the ATLAS detector at the LHC. The searches are based on a data sample of proton-proton collisions at a centre-of-mass energy √s = 13 TeV, corresponding to an integrated luminosity of 138 fb−1. Leptonic (τ → ℓνℓντ) and hadronic (τ → hadrons ντ) decays of the τ-lepton are considered. Two background estimation techniques are employed: the MC-template method, based on data-corrected simulation samples, and the Symmetry method, based on exploiting the symmetry between electrons and muons in the Standard Model backgrounds. No significant excess of events is observed and the results are interpreted as upper limits on lepton-flavour-violating branching ratios of the Higgs boson. The observed (expected) upper limits set on the branching ratios at 95% confidence level, β(H → eτ) < 0.20% β(0.12%) and (H → μτ ) < 0.18% (0.09%), are obtained with the MC-template method from a simultaneous measurement of potential H → eτ and H → μτ signals. The best-fit branching ratio difference, β(H → μτ) → β(H → eτ), measured with the Symmetry method in the channel where the τ-lepton decays to leptons, is (0.25 ± 0.10)%, compatible with a value of zero within 2.5σ.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Physics Institute > Laboratory for High Energy Physics (LHEP)
10 Strategic Research Centers > Albert Einstein Center for Fundamental Physics (AEC)

UniBE Contributor:

Beck, Hans Peter, Chatterjee, Meghranjana, Franconi, Laura, Halser, Lea, Haug, Sigve, Ilg, Armin, Müller, Roman, O'Neill, Aaron Paul, Schefer, Meinrad Moritz, Weber, Michele


500 Science > 530 Physics









Date Deposited:

06 Feb 2024 16:59

Last Modified:

30 Jun 2024 02:21

Publisher DOI:


Additional Information:

Kollaboration - Es sind nur die Berner Autor*innen namentlich erwaehnt; the ATLAS collaboration

Uncontrolled Keywords:

Hadron-Hadron Scattering




Actions (login required)

Edit item Edit item
Provide Feedback