Search for long-lived stopped R-hadrons decaying out-of-time with pp collisions using the ATLAS detector
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(Published version)
Date
2013
Authors
Aad, G.
Abajyan, T.
Abbott, B.
Abdallah, J.
Abdel Khalek, S.
Abdinov, O.
Aben, R.
Abi, B.
Abolins, M.
AbouZeid, O.S.
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Journal article
Citation
Physical Review D: Particles, Fields, Gravitation and Cosmology, 2013; 88(11):112003-1-112003-30
Statement of Responsibility
G. Aad … P. Jackson … N. Soni … M. J. White … et al. (ATLAS collaboration)
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Abstract
An updated search is performed for gluino, top squark, or bottom squark R-hadrons that have come to rest within the ATLAS calorimeter, and decay at some later time to hadronic jets and a neutralino, using 5.0 and 22.9 fb -1 of pp collisions at 7 and 8 TeV, respectively. Candidate decay events are triggered in selected empty bunch crossings of the LHC in order to remove pp collision backgrounds. Selections based on jet shape and muon system activity are applied to discriminate signal events from cosmic ray and beam-halo muon backgrounds. In the absence of an excess of events, improved limits are set on gluino, stop, and sbottom masses for different decays, lifetimes, and neutralino masses. With a neutralino of mass 100 GeV, the analysis excludes gluinos with mass below 832 GeV (with an expected lower limit of 731 GeV), for a gluino lifetime between 10 μs and 1000 s in the generic R-hadron model with equal branching ratios for decays to qq̄χËœ0 and gχËœ0. Under the same assumptions for the neutralino mass and squark lifetime, top squarks and bottom squarks in the Regge R-hadron model are excluded with masses below 379 and 344 GeV, respectively.
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© 2013 CERN, for the ATLAS Collaboration. Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.