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Daniel Teyssier RWTH Aachen University

Searches for non-standard SUSY signatures in CMS. Daniel Teyssier RWTH Aachen University. on behalf of the CMS collaboration. Outline :. - physics goals - the CMS detector - two photons searches in GMSB - HSCP searches - conclusion. Physics goals. γγ final states in GMSB.

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Daniel Teyssier RWTH Aachen University

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  1. Searches for non-standard SUSY signatures in CMS Daniel Teyssier RWTH Aachen University on behalf of the CMS collaboration

  2. Outline : • - physics goals • - the CMS detector - two photons searches in GMSB - HSCP searches - conclusion

  3. Physics goals γγ final states in GMSB • mGMSB (minimal Gauge Mediated Supersymmetry Breaking) model, with SUSY breaking transmitted via gauge interactions (from hidden sector to visible sector), alternative to mSUGRA • 6 parameters to define the model : • Λ (SUSY breaking scale) • Mm (messenger mass scale) • Nm (number of SU(5) messenger multiplets) • Cgrav (NLSP lifetime) • tanβ • sign(µ) • Some sets of parameters give the neutralino as the NLSP and the gravitino as LSP, with BR(χ →γ) > 80% : as sparticles are produced in pairs, final states containγγwith high pT ~ ~ G

  4. Physics goals ~ ~ ~ HSCP (Heavy Stable Charged Particles), τ, g, t • Other sets of parameters in mGMSB model predict quasi-stable sleptons (stau) with masses greater than hundred GeV • UED (Universal Extra Dimension) model predicts also such quasi-stable sleptons, called KK (Kaluza-Klein) states, with cross-sections of the order of few fb • split SUSY (model with high scalar masses) permits the existence of long lived gluino • MSSM allows light stop to be the NLSP, with the only possible decay t->cХ and then a long lived stop • g and t hadronize to form R-hadrons : R-baryons (gqqq, t1qq), • R-mesons (gqq, t1q) and R-gluonball gg ~ ~ ~ ~ ~ ~ _ _ ~ ~ ~

  5. CMS detector Performances of the detector : Tracker : σpT/pT ≈ 1.5 ∙10-4 pT(GeV)+ 0.5% ECAL : σE/E ≈ 2.9%/√E(GeV) + 0.5% HCAL : σE/E ≈ 120%/√E(GeV) + 6.9% Muons : σpT/pT ≈ 5% for 1 TeV muons

  6. γγ GMSB • Signature : 2 high pT photons, large transverse missing energy (gravitino) and high pT jets • Selection based on : • high level trigger used : single γ • photon isolation criteria • pT (γ) > 80 GeV • pTmiss > 160 GeV • pT4j > 50 GeV q q ν l γ ~ ~ ~ ~ ~ g q χ+ l χ0 ~ G

  7. γγ GMSB • Main background : • QCD multijets and γ+jets : fake MET from mismeasured jets • tt and W+jets : electron could be misidentified as a photon, and possible large MET from neutrinos - -

  8. γγ GMSB • Significance estimated using likelihood ratio and toy experiments ∫Ldt to get 5 σ for L=140 TeV

  9. HSCP : detection techniques Muon-like signature but : - β lower than high relativistic muons (for both lepton-like and R-hadrons) - charge flipping for R-hadrons (trajectory modified and neutral R-hadrons not visible) R-hadrons do not shower in calorimeters : Average R-hadron energy loss per nuclear interaction according to different models hep-ph/0611040

  10. HSCP : β measurement dE/dx using inner tracker : TOF (Time Of Flight) using muon system : Non Relativistic Particle Non Relativistic Particle RPC (Resistive Plate Chamber) used to confirm the track, and reject the background, mainly badly measured muons and cosmic muons β-2 ≈ k dE/dX in 0.1<βγ<0.9 region k measured from proton sample Z → µµ sample used as control sample

  11. HSCP selection β-1 tk Samples used : • Signal : g, t1, mGMSB τ1, KK τ1 (full Geant4 and specific simulation for R-hadrons interactions : R Mackeprang, A Rizzi : Eur.Phys.J.C50:353-362,2007) • SM background : QCD, W/Z+jets, tt Selection criteria : • Muon : pT >30 GeV • Tracker : β-1tk>1.1, Nhits>8, χ²/ndof < 5 • Combined : β-1DT > 1.25, β-1tk> 1.25 with mavg > 100 GeV Mass measurement : • β taken as the average between (βtk,βDT) and momentum measured in muon system • the HSCP mass is calculated ~ ~ ~ ~ SM background - β-1 tk ~ t1 500GeV CMS AN-2007/049 β-1DT

  12. HSCP results • SM background and cosmic muons negligible • gluino and stop channels to be easily seen after the start-up • stau and KK states channels need more integrated luminosity ∫Ldt to get 5 σ Mass spectrum ~ ~ √s=14 TeV KK τ1 t1 ~ g √s=14 TeV ~ mGMSB τ Mass (GeV) Mass (GeV)

  13. Conclusion • γγ GMSB : - discovery possible at startup of the LHC - to cover models up to Λ~200 (300) TeV would need an integrated luminosity of 1 (100) fb-1 • HSCP : - high cross-sections and discovery potential from the startup at LHC - mGMSB staus or R-hadrons up to few hundred GeV could be seen in the first 100 pb-1 - KK states more challenging but feasible with more than 1fb-1 - other searches exist on stopped HSCP, that are decaying up to few hours/days after the production

  14. BACKUP

  15. Cross-sections

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