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@ARTICLE{Aad:461967,
      author       = {Aad, G. and others},
      collaboration = {{ATLAS Collaboration}},
      title        = {{T}est of the universality of $\tau$ and $\mu$ lepton
                      couplings in ${W}$-boson decays with the {ATLAS} detector},
      journal      = {Nature physics},
      volume       = {17},
      number       = {7},
      issn         = {1745-2481},
      address      = {Basingstoke},
      publisher    = {Nature Publishing Group},
      reportid     = {PUBDB-2021-03197},
      pages        = {813 - 818},
      year         = {2021},
      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 $t\overline{t}$ 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.},
      keywords     = {lepton, coupling (INSPIRE) / decay rate, ratio (INSPIRE) /
                      W, decay rate (INSPIRE) / ATLAS (INSPIRE) / muon (INSPIRE) /
                      universality (INSPIRE)},
      cin          = {$Z_ATLAS$},
      ddc          = {530},
      cid          = {$I:(DE-H253)Z_ATLAS-20210408$},
      pnm          = {621 - Accelerator Research and Development (POF4-621)},
      pid          = {G:(DE-HGF)POF4-621},
      experiment   = {EXP:(DE-H253)LHC-Exp-ATLAS-20150101},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000669764700003},
      doi          = {10.1038/s41567-021-01236-w},
      url          = {https://bib-pubdb1.desy.de/record/461967},
}