A search for a narrow Z ′ gauge boson with a mass between 5 and 70 GeV resulting from an L μ −L τ U(1) local gauge symmetry is reported. Theories that predict such a particle have been proposed as an explanation of various experimental discrepancies, including the lack of a dark matter signal in direct-detection experiments, tension in the measurement of the anomalous magnetic moment of the muon, and reports of possible lepton flavor universality violation in B meson decays. A data sample of proton-proton collisions at a center-of-mass energy of 13 TeV is used, corresponding to an integrated luminosity of 77.3 fb −1 recorded in 2016 and 2017 by the CMS detector at the LHC. Events containing four muons with an invariant mass near the standard model Z boson mass are analyzed, and the selection is further optimized to be sensitive to the events that may contain Z→Z ′ μμ→4μ decays. The event yields are consistent with the standard model predictions. Upper limits of 10 −8 –10 −7 at 95% confidence level are set on the product of branching fractions B(Z→Z ′ μμ)B(Z ′ →μμ), depending on the Z ′ mass, which excludes a Z ′ boson coupling strength to muons above 0.004–0.3. These are the first dedicated limits on L μ −L τ models at the LHC and result in a significant increase in the excluded model parameter space. The results of this search may also be used to constrain the coupling strength of any light Z ′ gauge boson to muons.

Sirunyan, A., Tumasyan, A., Adam, W., Ambrogi, F., Asilar, E., Bergauer, T., et al. (2019). Search for an L μ  − L τ gauge boson using Z → 4μ events in proton-proton collisions at s=13 TeV. PHYSICS LETTERS. SECTION B, 792, 345-368 [10.1016/j.physletb.2019.01.072].

Search for an L μ  − L τ gauge boson using Z → 4μ events in proton-proton collisions at s=13 TeV

Benaglia, A.;Beschi, A.;Brivio, F.;Ciriolo, V.;Dinardo, M. E.;Fiorendi, S.;Ghezzi, A.;Govoni, P.;Malberti, M.;Massironi, A.;Monti, F.;Moroni, L.;Paganoni, M.;Ragazzi, S.;Tabarelli de Fatis, T.;Zuolo, D.;Lucchini, M. T.;De Guio, F.;
2019

Abstract

A search for a narrow Z ′ gauge boson with a mass between 5 and 70 GeV resulting from an L μ −L τ U(1) local gauge symmetry is reported. Theories that predict such a particle have been proposed as an explanation of various experimental discrepancies, including the lack of a dark matter signal in direct-detection experiments, tension in the measurement of the anomalous magnetic moment of the muon, and reports of possible lepton flavor universality violation in B meson decays. A data sample of proton-proton collisions at a center-of-mass energy of 13 TeV is used, corresponding to an integrated luminosity of 77.3 fb −1 recorded in 2016 and 2017 by the CMS detector at the LHC. Events containing four muons with an invariant mass near the standard model Z boson mass are analyzed, and the selection is further optimized to be sensitive to the events that may contain Z→Z ′ μμ→4μ decays. The event yields are consistent with the standard model predictions. Upper limits of 10 −8 –10 −7 at 95% confidence level are set on the product of branching fractions B(Z→Z ′ μμ)B(Z ′ →μμ), depending on the Z ′ mass, which excludes a Z ′ boson coupling strength to muons above 0.004–0.3. These are the first dedicated limits on L μ −L τ models at the LHC and result in a significant increase in the excluded model parameter space. The results of this search may also be used to constrain the coupling strength of any light Z ′ gauge boson to muons.
Articolo in rivista - Articolo scientifico
CMS; Muons; Physics; Zprime; Nuclear and High Energy Physics
English
2019
792
345
368
none
Sirunyan, A., Tumasyan, A., Adam, W., Ambrogi, F., Asilar, E., Bergauer, T., et al. (2019). Search for an L μ  − L τ gauge boson using Z → 4μ events in proton-proton collisions at s=13 TeV. PHYSICS LETTERS. SECTION B, 792, 345-368 [10.1016/j.physletb.2019.01.072].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/228432
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