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Test of the universality of τ and μ lepton couplings in W-boson decays with the ATLAS detector

Aad, G ; Åkesson, Torsten LU orcid ; Bocchetta, Simona LU ; Corrigan, Eric Edward LU ; Doglioni, Caterina LU ; Geisen, Jannik LU orcid ; Gregersen, Kristian LU ; Brottmann Hansen, Eva LU ; Hedberg, Vincent LU and Jarlskog, Göran LU , et al. (2021) In Nature Physics 17(7). p.813-818
Abstract
The standard model of particle physics encapsulates our best current understanding of physics at the smallest scales. A fundamental axiom of this theory is the universality of the couplings of the different generations of leptons to the electroweak gauge bosons. The measurement of the ratio of the decay rate of W bosons to τ leptons and muons, R(τ/μ), constitutes an important test of this axiom. Using 139 fb−1 of proton–proton collisions recorded with the ATLAS detector at a centre-of-mass energy of 13 TeV, we report a measurement of this quantity from di-leptonic tt¯ events where the top quarks decay into a W boson and a bottom quark. We can distinguish muons originating from W bosons and those originating from an intermediate τ lepton... (More)
The standard model of particle physics encapsulates our best current understanding of physics at the smallest scales. A fundamental axiom of this theory is the universality of the couplings of the different generations of leptons to the electroweak gauge bosons. The measurement of the ratio of the decay rate of W bosons to τ leptons and muons, R(τ/μ), constitutes an important test of this axiom. Using 139 fb−1 of proton–proton collisions recorded with the ATLAS detector at a centre-of-mass energy of 13 TeV, we report a measurement of this quantity from di-leptonic tt¯ events where the top quarks decay into a W boson and a bottom quark. We can distinguish muons originating from W bosons and those originating from an intermediate τ lepton through the muon transverse impact parameter and differences in the muon transverse momentum spectra. The measured value of R(τ/μ) is 0.992 ± 0.013 [± 0.007(stat) ± 0.011(syst)] and is in agreement with the hypothesis of universal lepton couplings as postulated in the standard model. This is the only such measurement from the Large Hadron Collider, so far, and obtains twice the precision of previous measurements. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Nature Physics
volume
17
issue
7
pages
813 - 818
publisher
Nature Publishing Group
external identifiers
  • scopus:85111587526
ISSN
1745-2473
DOI
10.1038/s41567-021-01236-w
language
English
LU publication?
yes
id
189af38a-6fa2-48f7-9f0a-c87564c9580b
date added to LUP
2021-09-24 11:58:36
date last changed
2023-04-02 17:47:50
@article{189af38a-6fa2-48f7-9f0a-c87564c9580b,
  abstract     = {{The standard model of particle physics encapsulates our best current understanding of physics at the smallest scales. A fundamental axiom of this theory is the universality of the couplings of the different generations of leptons to the electroweak gauge bosons. The measurement of the ratio of the decay rate of W bosons to τ leptons and muons, R(τ/μ), constitutes an important test of this axiom. Using 139 fb−1 of proton–proton collisions recorded with the ATLAS detector at a centre-of-mass energy of 13 TeV, we report a measurement of this quantity from di-leptonic tt¯ events where the top quarks decay into a W boson and a bottom quark. We can distinguish muons originating from W bosons and those originating from an intermediate τ lepton through the muon transverse impact parameter and differences in the muon transverse momentum spectra. The measured value of R(τ/μ) is 0.992 ± 0.013 [± 0.007(stat) ± 0.011(syst)] and is in agreement with the hypothesis of universal lepton couplings as postulated in the standard model. This is the only such measurement from the Large Hadron Collider, so far, and obtains twice the precision of previous measurements.}},
  author       = {{Aad, G and Åkesson, Torsten and Bocchetta, Simona and Corrigan, Eric Edward and Doglioni, Caterina and Geisen, Jannik and Gregersen, Kristian and Brottmann Hansen, Eva and Hedberg, Vincent and Jarlskog, Göran and Kellermann, Edgar and Konya, Balazs and Lytken, Else and Mankinen, Katja and Marcon, Caterina and Mjörnmark, Ulf and Mullier, Geoffrey André Adrien and Pöttgen, Ruth and Poulsen, Trine and Skorda, Eleni and Smirnova, Oxana and Zwalinski, L}},
  issn         = {{1745-2473}},
  language     = {{eng}},
  number       = {{7}},
  pages        = {{813--818}},
  publisher    = {{Nature Publishing Group}},
  series       = {{Nature Physics}},
  title        = {{Test of the universality of τ and μ lepton couplings in W-boson decays with the ATLAS detector}},
  url          = {{http://dx.doi.org/10.1038/s41567-021-01236-w}},
  doi          = {{10.1038/s41567-021-01236-w}},
  volume       = {{17}},
  year         = {{2021}},
}