Search for the Production of a Long-Lived Neutral Particle Decaying within the ATLAS Hadronic Calorimeter in Association with a Z Boson from pp Collisions at s =13 TeV

Summary, in English

This Letter presents a search for the production of a long-lived neutral particle (Zd) decaying within the ATLAS hadronic calorimeter, in association with a standard model (SM) Z boson produced via an intermediate scalar boson, where Z→+ (=e, μ). The data used were collected by the ATLAS detector during 2015 and 2016 pp collisions with a center-of-mass energy of s=13 TeV at the Large Hadron Collider and correspond to an integrated luminosity of 36.1±0.8 fb-1. No significant excess of events is observed above the expected background. Limits on the production cross section of the scalar boson times its decay branching fraction into the long-lived neutral particle are derived as a function of the mass of the intermediate scalar boson, the mass of the long-lived neutral particle, and its cτ from a few centimeters to one hundred meters. In the case that the intermediate scalar boson is the SM Higgs boson, its decay branching fraction to a long-lived neutral particle with a cτ approximately between 0.1 and 7 m is excluded with a 95% confidence level up to 10% for mZd between 5 and 15 GeV. © 2019 CERN for the ATLAS Collaboration. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP 3 .

• Author: M Aaboud; Torsten Åkesson; Simona Bocchetta; Lene Bryngemark; Eric Corrigan; Caterina Doglioni; Kristian Gregersen; Eva Brottmann Hansen; Vincent Hedberg; Göran Jarlskog; Charles Kalderon; Edgar Kellermann; Balazs Konya; Else Lytken; Katja Mankinen; Caterina Marcon; Ulf Mjörnmark; Geoffrey Mullier; Ruth Pöttgen; Trine Poulsen; Oxana Smirnova; L Zwalinski
• Department/s: Particle and nuclear physics; eSSENCE: The e-Science Collaboration
• Publishing year: 2019
• Language: English
• Publication/Series: Physical Review Letters
• Volume: 122
• Issue: 15
• Links: http://dx.doi.org/10.1103/PhysRevLett.122.151801
• Document type: Journal article
• Publisher: American Physical Society
• Topic: Subatomic Physics
• Keywords: Calorimeters; Neutrons; Tellurium compounds; ATLAS detectors; Branching fractions; Confidence levels; Hadronic calorimeters; Integrated luminosity; Large Hadron Collider; Neutral particles; Production cross section; Bosons
• Status: Published
• ISBN/ISSN/Other: ISSN: 1079-7114