1 / 24

SUSY: RpV with ’. di-electrons events

SUSY: RpV with ’. di-electrons events. Auguste BESSON (ISN-Grenoble) SUSY framework, signal and topology Background and expected results First look at the data : 2 - electrons selections, what can we see ? Conclusion. SUSY framework.

abraham-salazar
Download Presentation

SUSY: RpV with ’. di-electrons events

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. SUSY: RpV with ’. di-electrons events Auguste BESSON(ISN-Grenoble) • SUSY framework, signal and topology • Background and expected results • First look at the data : 2 - electrons selections, what can we see ? • Conclusion. New Phenomena, December 14th 2001.

  2. SUSY framework • mSUGRA model : m0 , m1/2 , A0 , tan  , Sign  • R-parity violated : • Double production in Rp conservated • Decay of LSP via RpV. • One dominant coupling : L : left-handed lepton doublet Q : Quark doublet D : anti-quark singlet New Phenomena, December 14th 2001.

  3. Signal topology with ’122 • Vertex : • LSP decay with : • ’ can be small Without decreasing the signal. New Phenomena, December 14th 2001.

  4. Signal topology (2) • Final state. 2 LSP decay : • 2 like sign leptons with high pT + 4 jets + small missing Et. • Branching ratios of LSP  charged lepton : • depends strongly on Sign  . ( and m0 , m1/2, tan  ) • Example : Br.ratio very small for  > 0 . • some regions of the parameters space will be difficult to reach. New Phenomena, December 14th 2001.

  5. Background • 2 like sign electrons + 4 jets + small missing Et. • t-tbar :  6.5 pb • Z ee : • 20 < pT < 60 : 139 pb • 60 < pT < 120 : 165 pb • 120 < pT : 1.9 pb • Z  : • 20 < pT < 60 : 137 pb • 60 < pT < 120 : 164 pb • 120 < pT : 1.9 pb • WW/ZZ/ZW  leptons : 7 pb, 0.9 pb, 2 pb • W/Z + jets. • QCD with pT > 10. + e fake :  600 pb • Misidentification probability of the sign of the electrons ? • e fake probability ?  10-4 Need further studies. New Phenomena, December 14th 2001.

  6. Very preliminary study with SHW/PGS • SCAN in the SUGRA parameters space. • m0 : 50 to 500 step of 50. • m1/2 : 80 to 220 step of 10. • A0 : 0 • Tan  : 5 • Sign  : +1, -1. • 1000 events per point. New Phenomena, December 14th 2001.

  7. Trigger and events selection • Very simple selection: • 2 like sign electrons • pT > 10 GeV ;  < 1.0 • Jets : • pT > 10 GeV ;  < 2.0 • Invariant mass of e-e : not between 80 and 100 GeV. New Phenomena, December 14th 2001.

  8. Cross-sections m 0 m 0 m1/2 m1/2 New Phenomena, December 14th 2001.

  9. Efficiencies Very low efficiency (branching ratios of LSPelectrons small) m1/2 m1/2 m 0 m 0 New Phenomena, December 14th 2001.

  10. Efficiencies (2) • 20k to 50k events for each background. • No Bkgd events survived to the like sign leptons cuts. • The most difficult to estimate is QCD + efake backgd. • Very rough estimate of efficiences but promising results. New Phenomena, December 14th 2001.

  11. Exclusion contours • Very preliminary : • L = 200 pb-1 • 90% Conf. level. • Bakgd studies is only beginning. •  > 0 difficult to exclude. New Phenomena, December 14th 2001.

  12. Run I Exclusion contour for Sign  < 0 and tan  = 2 and 6. PRL 83, 4476 (1999) New Phenomena, December 14th 2001.

  13. Selection of 2 high pT leptons Data ( < Discussions Saclay-Grenoble) • Physics : Susy RpV final state in 2 leptons + X • Wich selection for 2 elec ? tried with p10.07.01, ~ 5 416 000 Evts, ~ 940 Runs. • Is it reasonnable ? yes if ~ 1% data New Phenomena, December 14th 2001.

  14. 2 electrons selection • P10.07.01, ~ 5 416 000 Evts, ~ 940 Runs. • Selections 2 electrons: • + “loose” cuts : • HMx41 < 700 && E > 5 • -0.2 < iso < 0.2 • 0.85 < Emfrac < 1.1 • 0.05 < Emfrac layer 1 < 1.0 • 0.05 < Emfrac layer 2 < 1.0 • 0.10 < Emfrac layer 3 < 0.8 • 0.01 < Emfrac layer 4 < 1.0 2 EMPART_S objets 454 465 events with 1 electron candidate i.e. ~ 8.4 % 20 073 events with >=2 electron candidates i.e. ~ 0.37 % New Phenomena, December 14th 2001.

  15. 2 electrons selection 2 EMPART_Z objets • P10.07.01, ~ 5 416 000 Evts, ~ 940 Runs. • Selections 2 electrons: + “loose” cuts. • + Eelectron > 10 GeV. • Tests on Monte-Carlo QCD pT > 2 GeV (p10.07), same cuts : 0 / 200 670 evts. (cellNN) 501 080 events with 1 electron candidate ~ 9.3 % 120 205 events with >=2 electron candidates ~ 2.2 % (thanks to Pavel Demine.) New Phenomena, December 14th 2001.

  16. Remarks • Hot cells : nNada = 0. • Hot towers : Not cut • Other selections raw data : sel. 2 electrons of the W/Z group • Emreco cuts • 5 < pT < 200 • EMfr != 1.0 • iso != 0.0 ~ 2% of the evts. Can be used Why ? New Phenomena, December 14th 2001.

  17. what about Z  ee ? (CellNN) Tight cuts: HMx41 < 150 pT > 15  < 3 -0.05 < iso < 0.2 0.9 < Emfrac < 1.1 0.05 < Emfrac layer 1 < 1.0 0.05 < Emfrac layer 2 < 0.6 0.25 < Emfrac layer 3 < 0.8 0.001 < Emfrac layer 4 < 0.5 nNADA = 0 pT1/pT2 < 3. flrS1 < 30. flrS2 < 50. 2.5 <| 1 - 2 | < 3.6 2.0 <| 1 - 2 | < 4.0 Auguste Besson

  18. Hot towers : not cut • Eta / phi. (all EMPART objects) New Phenomena, December 14th 2001.

  19. Emfrac(S_EM block)of all Em candidates • Why do we have some candidates with Emfrac < 0.8 in this block ? Auguste Besson

  20. What about jets ? (JCCA block) • Same 2e selection + selection of jets • Phi vs. Eta • quality Cuts: 0.05 < JCCAEMF < 0.95 JCCACHF < 0.4 JCCAHotF < 10. JCCAn90 > 1 JCCAE > 8. New Phenomena, 14th 2001.

  21. Selection 2 el + 4 jets • Same 2e selection : HMx41 < 150 pT > 15  < 3 -0.05 < iso < 0.2 0.9 < Emfrac < 1.1 0.05 < Emfrac layer 1 < 1.0 0.05 < Emfrac layer 2 < 0.6 0.25 < Emfrac layer 3 < 0.8 0.001 < Emfrac layer 4 < 0.5 nNADA = 0 • 20 073 2 events with 2 el candidates : • 115 events left with the 2 el cuts • 64 events left with at least 2 jets • 2 events left with 4 jets. • selection of at least 4 jets: 0.05 < JCCAEMF < 0.95 JCCACHF < 0.4 JCCAHotF < 10. JCCAn90 > 1 JCCAE > 8. pT > 10. JCCAdEta < 0.8 or JCCAdEta > 1.2

  22. Display

  23. Conclusion • Thanks to like sign dilepton cut : Exclusion contours should be improved significantly even with 100 or 200 pb-1. • For more confident results : Full reconstruction and/or PMCS. • Use W/Z group selection for the raw data. • Quality cuts for electrons/jets need to be optimized. New Phenomena, December 14th 2001.

  24. Feynman diagrams New Phenomena, December 14th 2001.

More Related