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Title: Search for decays of stopped long-lived particles produced in proton–proton collisions at $$\sqrt{s}= 8\,\text {TeV} $$

A search has been performed for long-lived particles that could have come to rest within the CMS detector, using the time intervals between LHC beam crossings. The existence of such particles could be deduced from observation of their decays via energy deposits in the CMS calorimeter appearing at times that are well separated from any proton–proton collisions. Using a data set corresponding to an integrated luminosity of 18.6 fb-1 of 8 TeV proton–proton collisions, and a search interval corresponding to 281 h of trigger livetime, 10 events are observed, with a background prediction of 13.2+3.6 -2.5 events. Limits are presented at 95 % confidence level on gluino and top squark production, for over 13 orders of magnitude in the mean proper lifetime of the stopped particle. Assuming a cloud model of R-hadron interactions, a gluino with mass ≤1000 GeV and a top squark with mass ≤525 GeV are excluded, for lifetimes between 1 µs and 1000 s. Finally, these results are the most stringent constraints on stopped particles to date.
Authors:
 [1]
  1. Yerevan Physics Inst. (YerPhI), Yerevan (Armenia). et al.
Publication Date:
OSTI Identifier:
1221233
Report Number(s):
FERMILAB-PUB--15-074-CMS; CERN-PH-EP--2015-002; CMS-EXO--12-036
Journal ID: ISSN 1434-6052; arXiv eprint number arXiv:1501.05603
Grant/Contract Number:
AC02-07CH11359
Type:
Accepted Manuscript
Journal Name:
European physical journal. C, Particles and fields (Online)
Additional Journal Information:
Journal Name: European physical journal. C, Particles and fields (Online); Journal Volume: 75; Journal Issue: 4; Journal ID: ISSN 1434-6052
Publisher:
Springer
Research Org:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
CMS Collaboration
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS