1. Sparticle reconstruction methods in the CMS detector Massimiliano Chiorboli Universita and INFN Catania

2. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting OutlineOutline Past studies on SUSY in CMS Recent studies: sparticle recontruction Decay chain 2 0 l + l - 1 0 Sparticles reconstruction: 2 0 l + l - 1 0 dilepton edge Sbottom recontstruction Gluino reconstruction measurement Conclusions

3. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Sparticle searches in CMS Up to now… Inclusive studies: Excess over the SM Now… Sparticle reconstruction

4. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting The CMS detector

5. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting 99.6 1 0 = LSP 186.0 1 ± 145.8lRlR 379.7 2 ± 211.4lLlL 186.8 2 0 549qRqR 358.8 3 0 570qLqL 379.1 4 0 549.7bRbR 600.5tRtR 522.5bLbL 412.5tLtL 643.3g Proposed Post-LEP Benchmarks for Supersymmetry (hep-ph/0106204) PYTHIA 6.152

6. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Decay chain p p b b (15% b L, 10% b R ) (35 % b L, 22% b R ) (0.2 %) (60 %) Event final state: 2 high p t isolated leptons OS 2 high p t b jets missing E t

7. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Event production 2 isolated leptons, p T >15 GeV, | |<2.4 2 b-jets, p T >20 GeV, | |<2 PYTHIA 6.152 CMSJET 4.801: fast simulation, parametrization of the detector SM bkg: tt, Z+jet, W+jet, ZZ, WW, ZW

8. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting First step: 2 0 l + l - 1 0 p p b b SUSY SUSY + SM 10 fb -1 Z+jet tt

9. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting E t miss > 50 GeV 10 fb -1

10. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Dilepton Edge Fit result:

11. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Sbottom reconstruction p p b b Assuming M( 1 0 ) known!

12. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Sbottom reconstruction E t miss > 50 GeVE t miss > 100 GeVE t miss > 150 GeV I choose the most energetic b-jet MC true

13. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Sbottom mass Result of fit: Generated masses: 10 fb -1

14. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Gluino reconstruction p p b b E t miss > 150 GeV

15. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Gluino mass Result of fit: Generated mass: 10 fb -1

16. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Combinatorial suppression (8%) b-jets from sbottoms of real decay chain have a harder spectrum

17. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Combinatorial suppression E b-jet 1 > 250 GeV SbottomGluino 10 fb -1

18. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Combinatorial suppression Sbottom Gluino 10 fb -1 E b-jet 1 > 250 GeV

19. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Sbottom mass Result of fit: Generated masses: 10 fb -1

20. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Gluino mass Generated mass: Result of fit: 10 fb -1

21. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Dependence on M( ) M( 1 0 ) true M( 1 0 ) = M(ll) M( 1 0 ) = M edge I assumed M( 1 0 ) known: we cannot detect the neutralinos! Sbottom Gluino

22. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Realistic situation Sbottom Gluino 5% 3%

23. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting estimation estimation doesnt depend on M( 1 0 ) !

24. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting estimation estimation Result of fit: Generated values: 10 fb -1

25. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Dependence on M(ll) Sbottom Gluino

26. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting With 60 fb -1 SbottomGluino

27. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Sbottoms separation 10 6 Detector resolution prevents the two sbottom separation

28. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting 152.5 1 0 = LSP 294.5 1 ± 193.4lRlR 546.1 2 ± 299.6lLlL 294.8 2 0 780qRqR 532.4 3 0 814qLqL 545.3 4 0 771.3bRbR 800.8tRtR 723.0bLbL 589.4tLtL 919.8g Point G

29. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting (16%) (8 %) Decay chain (16% b L, 10% b R ) (15 % b L, 28% b R ) (8 %) (60 %) Less good events More fake events

30. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Dilepton Edge 60 fb -1 SUSY only l slepton l E(ll) > 160 GeV

31. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Dilepton Edge E t miss > 100 GeVE t miss > 50 GeVE t miss > 150 GeV E(ll) > 160 GeV

32. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Dilepton Edge E(ll) > 160 GeVE t miss > 250 GeV

33. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Peaks reconstruction E t miss > 250 GeV Sbottom Gluino M(g)-M(b)

34. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Peaks reconstruction E t miss > 250 GeVE b-jet 1 > 300 GeV SbottomGluinoM(g)-M(b)

35. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Point G with 500 fb -1 No Pile Up! Fit result: E t miss > 250 GeV

36. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Sbottom at point G Result of fit: Generated masses: 500 fb -1

37. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting Gluino at point G Result of fit: Generated mass: 500 fb -1

38. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting at point G at point G Result of fit: Generated values: 500 fb -1

39. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting ConclusionsConclusions estimation of M(l + l - ) max sbottom reconstruction with Resol. ~ 13 %, but 2 sbottoms not resolved gluino reconstruction with Resol. 6 % M(g) - M(b) estimation, independent of M( 1 0 ), with Err ~ 4 % Point B (tan =10, low masses), with 10 fb -1 In some mSUGRA regions CMS will be able to obtain information about the mass spectrum of sparticles from dilepton edges and to reconstruct some sparticles mass peaks:

40. Massimiliano Chiorboli 18-20 Apr 2002 Euro-GDR Meeting ConclusionsConclusions Point G (tan =20, higher masses), with 500 fb -1 estimation of M(l + l - ) max sbottom reconstruction with Resol. ~ 7% gluino reconstruction with Resol. 6 % M(g) - M(b) estimation, independent of M( 1 0 ), with Err ~ 4 %