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Search for charged-lepton-flavour violation in Z-boson decays with the ATLAS detector

Aad, G. ; Åkesson, T.P.A. LU orcid ; Bocchetta, S.S. LU ; Corrigan, E.E. LU ; Doglioni, C. LU ; Geisen, J. LU orcid ; Gregersen, K. LU ; Hansen, E. LU ; Hedberg, V. LU and Jarlskog, G. LU , et al. (2021) In Nature Physics 17(7). p.819-825
Abstract
Leptons with essentially the same properties apart from their mass are grouped into three families (or flavours). The number of leptons of each flavour is conserved in interactions, but this is not imposed by fundamental principles. Since the formulation of the standard model of particle physics, the observation of flavour oscillations among neutrinos has shown that lepton flavour is not conserved in neutrino weak interactions. So far, there has been no experimental evidence that this also occurs in interactions between charged leptons. Such an observation would be a sign of undiscovered particles or a yet unknown type of interaction. Here the ATLAS experiment at the Large Hadron Collider at CERN reports a constraint on... (More)
Leptons with essentially the same properties apart from their mass are grouped into three families (or flavours). The number of leptons of each flavour is conserved in interactions, but this is not imposed by fundamental principles. Since the formulation of the standard model of particle physics, the observation of flavour oscillations among neutrinos has shown that lepton flavour is not conserved in neutrino weak interactions. So far, there has been no experimental evidence that this also occurs in interactions between charged leptons. Such an observation would be a sign of undiscovered particles or a yet unknown type of interaction. Here the ATLAS experiment at the Large Hadron Collider at CERN reports a constraint on lepton-flavour-violating effects in weak interactions, searching for Z-boson decays into a τ lepton and another lepton of different flavour with opposite electric charge. The branching fractions for these decays are measured to be less than 8.1 × 10−6 (eτ) and 9.5 × 10−6 (μτ) at the 95% confidence level using 139 fb−1 of proton–proton collision data at a centre-of-mass energy of s=13TeV and 20.3 fb−1 at s=8TeV. These results supersede the limits from the Large Electron–Positron Collider experiments conducted more than two decades ago. © 2021, The Author(s), under exclusive licence to Springer Nature Limited. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Branching fractions, Centre-of-mass energies, Experimental evidence, Fundamental principles, Large Hadron Collider, Proton collisions, The standard model, Weak interactions, Bosons
in
Nature Physics
volume
17
issue
7
pages
7 pages
publisher
Nature Publishing Group
external identifiers
  • scopus:85111765683
ISSN
1745-2473
DOI
10.1038/s41567-021-01225-z
language
English
LU publication?
yes
id
299691f7-c16b-448f-abe1-c2a0cbd0f116
date added to LUP
2022-09-05 09:28:01
date last changed
2023-04-06 11:48:10
@article{299691f7-c16b-448f-abe1-c2a0cbd0f116,
  abstract     = {{Leptons with essentially the same properties apart from their mass are grouped into three families (or flavours). The number of leptons of each flavour is conserved in interactions, but this is not imposed by fundamental principles. Since the formulation of the standard model of particle physics, the observation of flavour oscillations among neutrinos has shown that lepton flavour is not conserved in neutrino weak interactions. So far, there has been no experimental evidence that this also occurs in interactions between charged leptons. Such an observation would be a sign of undiscovered particles or a yet unknown type of interaction. Here the ATLAS experiment at the Large Hadron Collider at CERN reports a constraint on lepton-flavour-violating effects in weak interactions, searching for Z-boson decays into a τ lepton and another lepton of different flavour with opposite electric charge. The branching fractions for these decays are measured to be less than 8.1 × 10−6 (eτ) and 9.5 × 10−6 (μτ) at the 95% confidence level using 139 fb−1 of proton–proton collision data at a centre-of-mass energy of s=13TeV and 20.3 fb−1 at s=8TeV. These results supersede the limits from the Large Electron–Positron Collider experiments conducted more than two decades ago. © 2021, The Author(s), under exclusive licence to Springer Nature Limited.}},
  author       = {{Aad, G. and Åkesson, T.P.A. and Bocchetta, S.S. and Corrigan, E.E. and Doglioni, C. and Geisen, J. and Gregersen, K. and Hansen, E. and Hedberg, V. and Jarlskog, G. and Kellermann, E. and Konya, B. and Lytken, E. and Mankinen, K.H. and Marcon, C. and Mjörnmark, J.U. and Mullier, G.A. and Poettgen, R. and Poulsen, T. and Skorda, E. and Smirnova, O. and Zwalinski, L.}},
  issn         = {{1745-2473}},
  keywords     = {{Branching fractions; Centre-of-mass energies; Experimental evidence; Fundamental principles; Large Hadron Collider; Proton collisions; The standard model; Weak interactions; Bosons}},
  language     = {{eng}},
  number       = {{7}},
  pages        = {{819--825}},
  publisher    = {{Nature Publishing Group}},
  series       = {{Nature Physics}},
  title        = {{Search for charged-lepton-flavour violation in Z-boson decays with the ATLAS detector}},
  url          = {{http://dx.doi.org/10.1038/s41567-021-01225-z}},
  doi          = {{10.1038/s41567-021-01225-z}},
  volume       = {{17}},
  year         = {{2021}},
}