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Progress on SUSY particles reconstruction methods Massimiliano Chiorboli Università di Catania.

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Presentation on theme: "Progress on SUSY particles reconstruction methods Massimiliano Chiorboli Università di Catania."— Presentation transcript:

1 Progress on SUSY particles reconstruction methods Massimiliano Chiorboli Università di Catania

2 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting mSUGRA Points Proposed Post-LEP Benchmarks for Supersymmetry (hep-ph/ ) High total SUSY cross section we can try to reconstruct masses with low integrated luminosity

3 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Point B m0m0 100 GeV m 1/2 250 GeV tan  10 A0A0 0 sign  + g643.3tLtL bLbL 522.5tRtR bRbR 40 qLqL 570 30 qRqR 549 20 lLlL 2±2± lRlR 1±1±  1 0 = LSP 99.6

4 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Decay chain and event topology (26 %) (35 %) (0.2 %) (60 %) p p b b Event final state:  2 high p t isolated leptons OS  2 high p t b jets missing E t

5 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Events Production SPYTHIA (PYTHIA 6.136) CMSJET SUSY (10 fb -1 ) ll 3912  gg 4420 gg qq qg tt qq qb 3423 bb 5959 bg 4280 Total SM tt6.2×10 6 (= 10 fb -1 ) Z+jet (p t hat >60)8×10 6 (< 10 fb -1 ) W+jet (p t hat >60)3×10 6 (< 10 fb -1 ) ZZ,WW,ZW2×10 6 (> 10 fb -1 ) No pile-up

6 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Events selection at least 2 isolated leptons with p t >10 GeV and |  |<2.5 at least 2 b-jets with p t >15 GeV and |  |<2 SUSY (10 fb -1 )% ll 0  gg gg qq qg tt qq qb bb bg SM tt20770 (0.04 %) Z+jet (p t hat >60)68 ( /10 6 ) W+jet (p t hat >60)0 ( /10 6 ) ZZ,WW,ZW32 ( /10 6 )

7 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Reconstruction of SUSY SM SUSY + SM PYTHIA Signal CMSJET

8 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Subtracting invariant mass of OSOF pairs eliminate tt and combinatorial bkg, but not Z+jet Other cuts Reconstruction of

9 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Reconstruction of

10 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Reconstruction of Result of fit: Generated value:

11 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting reconstruction

12 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Sbottom reconstruction reconstructed neutralino combined with the most energetic b-jet, assuming M   known SUSY Signal SUSY bkg qgqq gg qq gg  bbtt bgll qb Cutting on E t miss allows to suppress the SM bkg

13 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting 2 sbottoms E t miss > 100 GeV E t miss > 150 GeV we can’t resolve the 2 peaks Sbottom reconstruction 10 fb -1

14 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting M(b) estimation Result of fit: Generated masses:

15 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Estimation of M llb max PYTHIA Signal total

16 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Estimation of M llb max Result of fit:

17 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Gluino Reconstruction SUSY Signal SUSY bkg qgqq gg qq gg  bgtt ll bb qb Another b-jet is associated to the recostructed sbottom the b-jet closest in angle to the reconstructed sbottom is chosen

18 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Gluino Reconstruction E t miss > 50 GeVE t miss > 100 GeVE t miss > 150 GeV

19 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Gluino Reconstruction Result of fit: Generated mass:

20 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Combinatorial suppression

21 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Gluino after angle cut 10 fb -1

22 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Sbottom after angle cut 10 fb -1

23 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Estimation of doesn’t depend on M(  1 0 ) !

24 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Estimation of Result of fit: From the model:

25 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Sbottom and Gluino reconstruction With 40 fb -1 No angle cuts sbottomgluino Only SUSY E t miss > 150 GeV

26 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting With 40 fb -1 sbottom Generated values

27 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting With 40 fb -1 gluino Generated value

28 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting With 40 fb -1 no  cut

29 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Point G + sign  0A0A0 20 tan  375 GeVm 1/2 120 GeVm0m  1 0 = LSP 1±1± 193.4lRlR 2±2± 299.6lLlL 2020 780qRqR 3030 814qLqL 40 bRbR 800.8tRtR 723.0bLbL 589.4tLtL 919.8g

30 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Point G (26 %) (44 %) (8.8 %)

31 31/10/2001 Massimiliano Chiorboli CMS Physics Meeting Conclusions estimation of M(l + l - ) max estimation of M(l + l - b) max sbottom reconstruction with Resol. ~ 10 %, but 2 sbottoms not resolved gluino reconstruction with Resol. ~ 12 % M(g) - M(b) estimation, independent from M(  1 0 ), with Err ~ 7 % Point B, with 10 fb -1 Point G, with 60 fb -1 No sbottom reconstruction, needs more investigation


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