Searches for lepton-flavour-violating decays of the Higgs boson into $e\tau$ and $\mu\tau$ in $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector

Aad, Georges; Abbott, Braden Keim; Abbott, D.C.; Abeling, Kira; Abidi, Haider; Aboulhorma, Asmaa; Abramowicz, Halina; Abreu, Henso; Abulaiti, Yiming; Abusleme Hoffman, A.C.

doi:10.1007/JHEP07(2023)166

Searches for lepton-flavour-violating decays of the Higgs boson into $e\tau$ and $\mu\tau$ in $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector

ATLAS

Collaboration

Feb 10, 2023

71 pages

Published in:

JHEP 07 (2023) 166

Published: Jul 21, 2023

e-Print:

2302.05225 [hep-ex]

DOI:

10.1007/JHEP07(2023)166

PDG:

{{\mathit H}}

\rightarrow

{{\mathit e}}{{\mathit \tau}}

Report number:

CERN-EP-2022-279

Experiments:

CERN-LHC-ATLAS

View in:

datasets

reference search44 citations

Citations per year

Abstract: (Springer)

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

\sqrt{s}

= 13 TeV, corresponding to an integrated luminosity of 138 fb

^{−1}

. Leptonic (τ → ℓν

_{ℓ}

ν

_{τ}

) and hadronic (τ → hadrons ν

_{τ}

) 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,

\mathcal{B}

(H → eτ) < 0.20% (0.12%) and

\mathcal{B}

(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,

\mathcal{B}

(H → μτ) →

\mathcal{B}

(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.[graphic not available: see fulltext]

Note:

71 pages in total, author list starting on page 54, 16 figures, 13 tables, published in JHEP 07 (2023) 166. All figures including auxiliary material are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2019-11

Hadron-Hadron Scattering
p p: colliding beams
Higgs particle: leptonic decay
Higgs particle: rare decay
p p: scattering
lepton: flavor: violation
Higgs particle: branching ratio
branching ratio: upper limit
background
ATLAS

References(120)

Figures(44)

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