Search for Invisible Decays of a Higgs Boson Produced in Association with a Z Boson in ATLAS


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Aad G., Abajyan T., Abbott B., Abdallah J., Khalek S. A., Abdinov O., ...More

PHYSICAL REVIEW LETTERS, vol.112, no.20, 2014 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 112 Issue: 20
  • Publication Date: 2014
  • Doi Number: 10.1103/physrevlett.112.201802
  • Journal Name: PHYSICAL REVIEW LETTERS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Middle East Technical University Affiliated: Yes

Abstract

A search for evidence of invisible-particle decay modes of a Higgs boson produced in association with a Z boson at the Large Hadron Collider is presented. No deviation from the standard model expectation is observed in 4.5 fb(-1) (20.3 fb(-1)) of 7 (8) TeV pp collision data collected by the ATLAS experiment. Assuming the standard model rate for ZH production, an upper limit of 75%, at the 95% confidence level is set on the branching ratio to invisible-particle decay modes of the Higgs boson at a mass of 125.5 GeV. The limit on the branching ratio is also interpreted in terms of an upper limit on the allowed dark matter-nucleon scattering cross section within a Higgs-portal dark matter scenario. Within the constraints of such a scenario, the results presented in this Letter provide the strongest available limits for low-mass dark matter candidates. Limits are also set on an additional neutral Higgs boson, in the mass range 110 < m(H) < 400 GeV, produced in association with a Z boson and decaying to invisible particles.