WIN 05

1. WIN 05 Supersymmetry searches at the LHC Filip Moortgat, CERN • Inclusive signatures: • discovery, fast but not unambiguous • Exclusive final states & long term measurements: • towards understanding the underlying model Filip Moortgat, CERN

2. Why SUSY is a good idea One of the most appealing extensions of the Standard Model: TeV-scale supersymmetry [= a symmetry between fermions and bosons, duplicates the SM particle spectrum, but not the couplings] Solves several problems at once: • dark matter candidate (e.g. lightest neutralino) • opening towards a theory of gravity • unification of gauge couplings • hierarchy problem • allows to explain why the Higgs mechanism works Filip Moortgat, CERN

3. SUSY models • In general MSSM: many allowed soft SUSY breaking parameters (124) due to unknown nature of SUSY breaking mechanism = difficult to work with  use more constrained models • Most popular: mSUGRA • Also mGMSB, AMSB m0 , m1/2 , A0 , tan b, sign(m) Filip Moortgat, CERN

4. The Large Hadron Collider (8 T !!) also AA and pA collisions; for PbPb : 5.5 TeV/nucleon and L = 1027 cm-2s-1 Filip Moortgat, CERN

5. Generic SUSY signatures • General characteristics of R-parity conserving SUSY: • sparticles pair produced and LSP stable •  large amount of missing transverse energy • coloured sparticles are copiously produced and cascade down to the LSP with emission of • many hard jets and often leptons Generic SUSY signatures are ETmiss + multi-jets (andmulti-leptons) Filip Moortgat, CERN

6. Inclusive SUSY • jets + ETmiss • 1,2,3 lepton + ETmiss • opposite sign (OS) or • same sign (SS) di-leptons • often several topologies • simultaneously visible Filip Moortgat, CERN

7. Jet + MET • Signature: ETmiss + jets • s ~ 1 pb at 1 TeV • → physics for startup • significant reach after 1 yr • with 300 fb-1, reach squarks and gluinos up to ~ 2.5 TeV • (need good understanding of • detector and backgrounds!) Filip Moortgat, CERN

8. Et sum [Branson et al, ATLAS] Variable that gives information on the “SUSY scale”: SM background SUSY (700 GeV) Warning: model dependent plot! Filip Moortgat, CERN

9. Same-sign dileptons Signal: Background: _  ask for 2 SS leptons + hard jets + ETmiss [Drozdetski et al, CMS] Filip Moortgat, CERN

10. Exclusive final states • so far: inclusive measurements • fast discovery, but does not • unambiguously single out SUSY • need to reconstruct sparticle decay chains and masses involved • need to be prepared for all possible final states • goal is to measure cross sections, BR’s ( couplings) • and even spin of the sparticles • LHC can not only discover SUSY, but • also MEASURE its properties (if nature is kind) Filip Moortgat, CERN

11. Region 1 • Region 2, e.g. • Region 3 Coloured sparticle decays [Pape, CMS] Filip Moortgat, CERN

12. Neutralino2 decay signatures Significant fraction of [Pape, CMS] Filip Moortgat, CERN

13. Decay chain to dileptons Final state: • 2 high pt isolated leptons • 2 high pt jets • missing Et

14. Kinematic endpoints Kinematic endpoint technique: construct lepton/quark upper/lower endpoints and relate them to the masses in the decay chain E.g.: 4 unknown masses: 4 endpoints:  all masses can be determined Usually non-linear relations  all masses, not just differences Extra endpoints, or start from gluino  constraints Filip Moortgat, CERN

15. Final states with dileptons (1) • M(ll): very sharp end point, triangular shape (due to spinless slepton)  [Chiorboli et al, CMS] [Biglietti et al, ATLAS]

16. Final states with dileptons (2) • M(l1q): • M(l2q): Can distinguish M(l1q)max from M(l2q)max • M(llq): M(llq) [ATLAS]

17. Gluino reconstruction Choose dilepton pairs close to the edge; then assuming can be at rest in the frame of  can reconstruct and [Chiorboli et al, CMS]

18. Final state with taus • often decays to taus instead of electrons/muons • can we use hadronic tau final states? endpoint smeared out [Biglietti et al, ATLAS]

19. Decay chain to h0 or Z0

20. Final states with h0 or Z0 [Paige, ATLAS] • Higgs peak can be reconstructed from 2 b-jets  could be a h0discovery channel ! (even for light H0 and A0) • Z0 reconstructed from di-lepton decay • Decay chain is shorter than for di-leptons  e.g. start from gluino M(q1h0),M(q2h0),M(qq),M(qqh0) to determine 4 masses M(bb) h0 [Moortgat, CMS] A0,H0

21. GMSB signatures In GMSB, the light gravitino is the LSP • Who is NLSP? • Neutralino is NLSP • Stau is NLSP  ETmiss +  ,  or long-lived particles TOF measurement in the CMS muon DT’s [Wrochna, CMS]  dE/dx and TOF

22. SUSY spin measurement Make use of spin correlations in decay of squark: [Barr, ATLAS] no spin correlations

23. SUSY spin measurements (2) washes out for antisquarks, but in pp colliders  more squarks produced than antisquarks [Barr, ATLAS] • Visible asymmetry: (500 fb-1) no spin correlations

24. Conclusions • If TeV-scale SUSY exists, its discovery at the LHC should be (relatively) fast, using inclusive signatures • The LHC can measure sparticle properties: reconstruction of masses in sparticle decay chains, mainly using kinematic endpoints • Ultimately would like to measure spins and couplings • (WIN 05  WINO 5?) • only 750 days to startup … so focusing on being ready for first day physics now! Filip Moortgat, CERN

25. Backup Filip Moortgat, CERN

26. Cross sections @ the LHC “Well known”processes, don’t need to keep all of them … New Physics!! This we want to keep!! Filip Moortgat, CERN

27. CMS Filip Moortgat, CERN

28. ATLAS Filip Moortgat, CERN

29. Civil Engineering USC 55 UXC 55 Filip Moortgat, CERN

30. Higgs to sparticles If accessible, we may exploit the sparticle decay modes: A, H  20 20  4l+ ETmiss Filip Moortgat, CERN