1 / 15

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.

shanon
Download Presentation

Daniel Teyssier RWTH Aachen University

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related