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Search for neutral long-lived particles that decay into displaced jets in the ATLAS calorimeter in association with leptons or jets using pp collisions at s = 13 TeV

Aad, G. ; Åkesson, T.P.A. LU orcid ; Astrand, K.S.V. LU ; Doglioni, C. LU ; Ekman, P.A. LU orcid ; Hedberg, V. LU ; Herde, H. LU orcid ; Konya, B. LU ; Lytken, E. LU orcid and Poettgen, R. LU orcid , et al. (2024) In Journal of High Energy Physics 2024(11).
Abstract
A search for neutral long-lived particles (LLPs) decaying in the ATLAS hadronic calorimeter using 140 fb−1 of proton-proton collisions at s = 13 TeV delivered by the LHC is presented. The analysis is composed of three channels. The first targets pair-produced LLPs, where at least one LLP is produced with sufficiently low boost that its decay products can be resolved as separate jets. The second and third channels target LLPs respectively produced in association with a W or Z boson that decays leptonically. In each channel, different search regions target different kinematic regimes, to cover a broad range of LLP mass hypotheses and models. No excesses of events relative to the background predictions are observed. Higgs boson branching... (More)
A search for neutral long-lived particles (LLPs) decaying in the ATLAS hadronic calorimeter using 140 fb−1 of proton-proton collisions at s = 13 TeV delivered by the LHC is presented. The analysis is composed of three channels. The first targets pair-produced LLPs, where at least one LLP is produced with sufficiently low boost that its decay products can be resolved as separate jets. The second and third channels target LLPs respectively produced in association with a W or Z boson that decays leptonically. In each channel, different search regions target different kinematic regimes, to cover a broad range of LLP mass hypotheses and models. No excesses of events relative to the background predictions are observed. Higgs boson branching fractions to pairs of hadronically decaying neutral LLPs larger than 1% are excluded at 95% confidence level for proper decay lengths in the range of 30 cm to 4.5 m depending on the LLP mass, a factor of three improvement on previous searches in the hadronic calorimeter. The production of long-lived dark photons in association with a Z boson with cross-sections above 0.1 pb is excluded for dark photon mean proper decay lengths in the range of 20 cm to 50 m, improving previous ATLAS results by an order of magnitude. Finally, long-lived photo-phobic axion-like particle models are probed for the first time by ATLAS, with production cross-sections above 0.1 pb excluded in the 0.1 mm to 10 m range. © The Author(s) 2024. (Less)
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type
Contribution to journal
publication status
published
subject
keywords
Beyond Standard Model, Exotics, Hadron-Hadron Scattering, Proton-Proton Scattering
in
Journal of High Energy Physics
volume
2024
issue
11
article number
36
publisher
Springer
external identifiers
  • scopus:85209988042
ISSN
1029-8479
DOI
10.1007/JHEP11(2024)036
language
English
LU publication?
yes
id
f02b0342-b6b5-4810-ab81-9841d8fb2f04
date added to LUP
2025-10-13 12:06:54
date last changed
2025-10-16 13:34:50
@article{f02b0342-b6b5-4810-ab81-9841d8fb2f04,
  abstract     = {{A search for neutral long-lived particles (LLPs) decaying in the ATLAS hadronic calorimeter using 140 fb−1 of proton-proton collisions at s = 13 TeV delivered by the LHC is presented. The analysis is composed of three channels. The first targets pair-produced LLPs, where at least one LLP is produced with sufficiently low boost that its decay products can be resolved as separate jets. The second and third channels target LLPs respectively produced in association with a W or Z boson that decays leptonically. In each channel, different search regions target different kinematic regimes, to cover a broad range of LLP mass hypotheses and models. No excesses of events relative to the background predictions are observed. Higgs boson branching fractions to pairs of hadronically decaying neutral LLPs larger than 1% are excluded at 95% confidence level for proper decay lengths in the range of 30 cm to 4.5 m depending on the LLP mass, a factor of three improvement on previous searches in the hadronic calorimeter. The production of long-lived dark photons in association with a Z boson with cross-sections above 0.1 pb is excluded for dark photon mean proper decay lengths in the range of 20 cm to 50 m, improving previous ATLAS results by an order of magnitude. Finally, long-lived photo-phobic axion-like particle models are probed for the first time by ATLAS, with production cross-sections above 0.1 pb excluded in the 0.1 mm to 10 m range. © The Author(s) 2024.}},
  author       = {{Aad, G. and Åkesson, T.P.A. and Astrand, K.S.V. and Doglioni, C. and Ekman, P.A. and Hedberg, V. and Herde, H. and Konya, B. and Lytken, E. and Poettgen, R. and Smirnova, O. and Wallin, E.J. and Zwalinski, L.}},
  issn         = {{1029-8479}},
  keywords     = {{Beyond Standard Model; Exotics; Hadron-Hadron Scattering; Proton-Proton Scattering}},
  language     = {{eng}},
  number       = {{11}},
  publisher    = {{Springer}},
  series       = {{Journal of High Energy Physics}},
  title        = {{Search for neutral long-lived particles that decay into displaced jets in the ATLAS calorimeter in association with leptons or jets using pp collisions at s = 13 TeV}},
  url          = {{http://dx.doi.org/10.1007/JHEP11(2024)036}},
  doi          = {{10.1007/JHEP11(2024)036}},
  volume       = {{2024}},
  year         = {{2024}},
}