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Searches for long-lived Particles with the CMS Detector

Searches for long-lived Particles with the CMS Detector. Lukas Vanelderen on behalf of the CMS Collaboration. Long-lived particles?. Beyond the Standard Model particles, produced in LHC collisions, that live long enough to cause anomalous signals in the LHC detectors. CMS-EXO-13-006.

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Searches for long-lived Particles with the CMS Detector

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  1. Searches for long-lived Particles with the CMS Detector Lukas Vanelderen on behalf of the CMS Collaboration

  2. Long-lived particles? • Beyond the Standard Model particles, produced in LHC collisions, that live long enough to cause anomalous signals in the LHC detectors

  3. CMS-EXO-13-006 • CMS-SUS-12-030 • 19D MSSM scan, with minimal assumptions (pMSSM),with constraints from pre-LHC and indirect measurements, sparticle masses allowed up to 3 TeV Why? • even in ‘dull’ R-parity conserving MSSM, long-lived particles are usual suspects… • … and there is a plethora of exotic models with plenty of long-lived particles

  4. Targets • Heavy Stable Charged Particles(HSCPs), singly, fractionally and multiply charged • Displaced decays of neutral particles • Displaced stop decays • … • NEW

  5. Search for Heavy Stable Charged Particles (HSCPs)CMS-EXO-12-026CMS-EXO-13-006

  6. CMS-EXO-12-026 • TrackerBethe Bloch relation for energy loss through ionization • each tracker hit provides dE/dX estimate => 3 tracker discriminators • - combined dE/dX estimate • - particle mass estimate • - likelihood discriminant HSCP tools • reconstructed as tracks and/or muonsproduced near threshold -> v/c < 1 • +

  7. CMS-EXO-12-026 HSCP tools • reconstructed as tracks and/or muonsproduced near threshold -> v/c < 1 • Muon systemestimate time of flight (TOF), based on arrival times of signals in muon system=> estimate c/v with resolution ~0.065 • +

  8. HSCP channels and results • CMS-EXO-12-026 • channels for singly charged HSCPs • focus on hadronic and lepton-like HSCPs • trigger: MET > 150 GeV OR Muon pt > 40 GeV • tracks: > 8 hits, very loosely isolated,dE/dX > 3 MeV/cm • muons: > 7 muon hits

  9. HSCP channels and results • CMS-EXO-12-026 • fractionally and multiply charged HSCPs • fractionally: tracker-only, de/dX < 2.8 MeV/cm • multiply: tracker + muon

  10. CMS-EXO-12-026 • CMS-EXO-13-006 • 19D MSSM scan, with minimal assumptions (pMSSM),with constraints from pre-LHC and indirect measurements, sparticle masses allowed up to 3 TeV re-interpretation • CMS-SUS-12-030 • Reinterpretation tools for HSCP search made public and applied on this 19D MSSM scan, sensitivity down to c*tau ~ 1m

  11. Searches for displaced decays of neutral particlesCMS-EXO-12-037CMS-EXO-12-038

  12. CMS-EXO-12-038 Neutral long-lived particles • Jet Channel • trigger HT > 300 GeV • search jet pairs,sharing, high-quality, displaced vertex jet pt > 60, eta < 2.0 • require at least 1 displaced track per jet(dxy > 500 µm) • define signal regions based on: • jet pair vertex dxy • for each jet: • # of non-displaced tracks • e-fraction of non-displaced tracks • mva discriminant based on • number of tracks in vertex • transverse vertex size • fraction of tracks with vertex beyond the jet pair vertex • +

  13. Neutral long-lived particles • CMS-EXO-12-037 • Lepton channel • Search ee (mumu) pairsharing displaced vertex • e: Et (track pt) > 40(36), 25(21) GeVmu: pt > 26 GeV, not back-to-back • Each track: - dxy/σ(dxy) > 12- isolated from other tracks • Not more than 1 hit in between primary and shared displaced vertex • M(ll) > 15 GeV • the displaced vertex must point within π/2 to the di-lepton momentum • 0 events predicted0 events observed • also available: • +

  14. NEW Search for displaced stop decaysCMS-B2G-12-024

  15. CMS-B2G-12-024 displaced stop decays • interpretation within“Displaced Supersymmetry” • P.Graham et al (JHEP 1207 (2012) 149.) • R-parity violating stop decays • 1 muon, 1 electron, - pt > 25 GeV, eta< 2.5- isolated from other particles- opposite charges • not inside jet with pt > 10 GeV • leptons: 0.1 mm < dxy < 20mm • +

  16. Summary • Nice set of tools to probe a range of models with long-lived particles • No excess observed, upper limits calculated for various models • Most analyses provide information to help re-interpretation in further models

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