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

The ATLAS Collaboration

Research output: Contribution to journalArticle

61 Citations (Scopus)

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 (formula presented) and (formula presented). 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.

Original languageEnglish
Article number112003
Pages (from-to)112003-1-112003-30
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume88
Issue number11
DOIs
Publication statusPublished - Jan 1 2013

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hadrons
collisions
detectors
decay
life (durability)
muons
calorimeters
cosmic rays
halos

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

Cite this

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

In: Physical Review D - Particles, Fields, Gravitation and Cosmology, Vol. 88, No. 11, 112003, 01.01.2013, p. 112003-1-112003-30.

Research output: Contribution to journalArticle

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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 (formula presented) and (formula presented). 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.",
author = "{The ATLAS Collaboration} and G. Aad and T. Abajyan and B. Abbott and J. Abdallah and {Abdel Khalek}, S. and O. Abdinov and R. Aben and B. Abi and M. Abolins and {Abou Zeid}, {O. S.} and H. Abramowicz and H. Abreu and Y. Abulaiti and Acharya, {B. S.} and L. Adamczyk and Adams, {D. L.} and Addy, {T. N.} and J. Adelman and S. Adomeit and T. Adye and S. Aefsky and T. Agatonovic-Jovin and Aguilar-Saavedra, {J. A.} and M. Agustoni and Ahlen, {S. P.} and A. Ahmad and F. Ahmadov and M. Ahsan and G. Aielli and {\AA}kesson, {T. P.A.} and G. Akimoto and Akimov, {A. V.} and Alam, {M. A.} and J. Albert and S. Albrand and {Alconada Verzini}, {M. J.} and M. Aleksa and Aleksandrov, {I. N.} and F. Alessandria and C. Alexa and G. Alexander and G. Alexandre and T. Alexopoulos and M. Alhroob and M. Aliev and G. Alimonti and L. Alio and J. Alison and Allbrooke, {B. M.M.} and Allison, {L. J.}",
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AU - Abdel Khalek, S.

AU - Abdinov, O.

AU - Aben, R.

AU - Abi, B.

AU - Abolins, M.

AU - Abou Zeid, O. S.

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AU - Abreu, H.

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AU - Adye, T.

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AU - Agatonovic-Jovin, T.

AU - Aguilar-Saavedra, J. A.

AU - Agustoni, M.

AU - Ahlen, S. P.

AU - Ahmad, A.

AU - Ahmadov, F.

AU - Ahsan, M.

AU - Aielli, G.

AU - Åkesson, T. P.A.

AU - Akimoto, G.

AU - Akimov, A. V.

AU - Alam, M. A.

AU - Albert, J.

AU - Albrand, S.

AU - Alconada Verzini, M. J.

AU - Aleksa, M.

AU - Aleksandrov, I. N.

AU - Alessandria, F.

AU - Alexa, C.

AU - Alexander, G.

AU - Alexandre, G.

AU - Alexopoulos, T.

AU - Alhroob, M.

AU - Aliev, M.

AU - Alimonti, G.

AU - Alio, L.

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N2 - 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 (formula presented) and (formula presented). 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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