Search for stopped long-lived particles produced in pp collisions at root s=7 TeV

Abstract

A search has been performed for long-lived particles that have stopped in the CMS detector, during 7TeV proton-proton operations of the CERN LHC. The existence of such particles could be inferred from observation of their decays when there were no proton-proton collisions in the CMS detector, namely during gaps between LHC beam crossings. Using a data set in which CMS recorded an integrated luminosity of 4.0 fb(-1), and a search interval corresponding to 246 hours of trigger live time, 12 events are observed, with a mean background prediction of 8.6 +/- 2.4 events. Limits are presented at 95% confidence level on long-lived gluino and stop production, over 13 orders of magnitude of particle lifetime. Assuming the "cloud model" of R-hadron interactions, a gluino with mass below 640 GeV and a stop with mass below 340 GeV are excluded, for lifetimes between 10 mu s and 1000s. ; FMSR ; FNRS and FWO ; CNPq, CAPES, FAPERJ, and FAPESP ; MES ; CERN; CAS, MoST, and NSFC ; COLCIENCIAS ; MSES ; RPF ; MoER, SF0690030s09 and ERDF ; Academy of Finland, MEC, and HIP ; CEA and CNRS/IN2P3 ; BMBF, DFG, and HGF ; GSRT ; OTKA and NKTH ; DAE and DST ; IPM ; SFI ; INFN ; NRF and WCU ; LAS ; CINVESTAV, CONACYT, SEP, and UASLP-FAI ; MSI ; PAEC ; MSHE and NSC ; FCT ; JINR ; MON, RosAtom, RAS and RFBR ; MSTD ; MICINN and CPAN ; Swiss Funding Agencies ; NSC ; TUBITAK and TAEK ; STFC ; DOE and NSF ; European Union ; the Leventis Foundation ; the A. P. Sloan Foundation ; the Alexander von Humboldt Foundation ; the Belgian Federal Science Policy Office; the Fonds pour la Formation `a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Council of Science and Industrial Research, India; and the HOMING PLUS programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund ; publisher version