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Scientific article
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English

Search for light long-lived neutral particles that decay to collimated pairs of leptons or light hadrons in pp collisions at $ \sqrt{s} $ = 13 tev with the atlas detector

ContributorsATLAS Collaboration
Published inThe journal of high energy physics, vol. 2023, 153
Publication date2023
First online date2023-06-23
Abstract

A search for light long-lived neutral particles with masses in the O(MeV–GeV) range is presented. The analysis targets the production of long-lived dark photons in the decay of a Higgs boson produced via gluon–gluon fusion or in association with a W boson. Events that contain displaced collimated Standard Model fermions reconstructed in the calorimeter or muon spectrometer are selected in 139 fb$^{−1}$ of $ \sqrt{s} $ = 13 TeV pp collision data collected by the ATLAS detector at the LHC. Background estimates for contributions from Standard Model processes and instrumental effects are extracted from data. The observed event yields are consistent with the expected background. Exclusion limits are reported on the production cross-section times branching fraction as a function of the mean proper decay length cτ of the dark photon, or as a function of the dark-photon mass and kinetic mixing parameter that quantifies the coupling between the Standard Model and potential hidden (dark) sectors. A Higgs boson branching fraction above 1% is excluded at 95% CL for a Higgs boson decaying into two dark photons for dark-photon mean proper decay lengths between 10 mm and 250 mm and dark photons with masses between 0.4 GeV and 2 GeV.

eng
Keywords
  • Exotics
  • Hadron-Hadron Scattering
  • P p: colliding beams
  • Decay: length
  • Neutral particle: long-lived
  • P p: scattering
  • Higgs particle: hadroproduction
  • W: associated production
  • Mixing: kinetic
  • Higgs particle: branching ratio: upper limit
  • Higgs particle: rare decay
  • Muon: spectrometer
  • Gluon gluon: fusion
  • Photon: pair production
  • Photon: hidden sector
  • Photon: mass
  • Mass: lower limit
  • Collimator
  • Background
  • ATLAS
  • Lepton: pair production
  • Calorimeter
  • CERN LHC Coll
  • Channel cross section: branching ratio: upper limit
  • Mass dependence
  • Experimental results
  • 13000 GeV-cms
Citation (ISO format)
ATLAS Collaboration. Search for light long-lived neutral particles that decay to collimated pairs of leptons or light hadrons in pp collisions at $ \sqrt{s} $ = 13 tev with the atlas detector. In: The journal of high energy physics, 2023, vol. 2023, p. 153. doi: 10.1007/jhep06(2023)153
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ISSN of the journal1029-8479
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