Search for dark photons in decays of Higgs bosons produced in association with Z bosons in proton-proton collisions at √s = 13 TeV


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Sirunyan A., Tumasyan A., Adam W., Ambrogi F., Bergauer T., Brandstetter J., ...More

Journal of High Energy Physics, vol.2019, no.10, 2019 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 2019 Issue: 10
  • Publication Date: 2019
  • Doi Number: 10.1007/jhep10(2019)139
  • Journal Name: Journal of High Energy Physics
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Keywords: Beyond Standard Model, Hadron-Hadron scattering (experiments), Photon production
  • Yıldız Technical University Affiliated: Yes

Abstract

A search is presented for a Higgs boson that is produced in association with a Z boson and that decays to an undetected particle together with an isolated photon. The search is performed by the CMS Collaboration at the Large Hadron Collider using a data set corresponding to an integrated luminosity of 137 fb−1 recorded at a center-of-mass energy of 13 TeV. No significant excess of events above the expectation from the standard model background is found. The results are interpreted in the context of a theoretical model in which the undetected particle is a massless dark photon. An upper limit is set on the product of the cross section for associated Higgs and Z boson production and the branching fraction for such a Higgs boson decay, as a function of the Higgs boson mass. For a mass of 125 GeV, assuming the standard model production cross section, this corresponds to an observed (expected) upper limit on this branching fraction of 4.6 (3.6)% at 95% confidence level. These are the first limits on Higgs boson decays to final states that include an undetected massless dark photon. [Figure not available: see fulltext.].