Search for long-lived stopped R-hadrons decaying out of time with pp collisions using the ATLAS detector

Allison, Lee and Barton, Adam and Borissov, Guennadi and Chilingarov, Alexandre and Dearnaley, William and Fox, Harald and Grimm, Kathryn and Henderson, Robert and Hughes, Gareth and Jones, Roger William Lewis and Kartvelishvili, Vakhtang and Long, Robin and Love, Peter and Maddocks, Harvey and Smizanska, Maria and Walder, James (2013) Search for long-lived stopped R-hadrons decaying out of time with pp collisions using the ATLAS detector. Physical Review D, 88 (11). ISSN 1550-7998

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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 qq¯χ˜0 and gχ˜0. 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.

Item Type:
Journal Article
Journal or Publication Title:
Physical Review D
Additional Information:
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. © 2013 CERN, for the ATLAS Collaboration
ID Code:
68486
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Deposited On:
03 Feb 2014 09:09
Refereed?:
Yes
Published?:
Published
Last Modified:
19 Sep 2020 02:58