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Update on Like-sign ee + jets channel

New Phenomena meeting. Update on Like-sign ee + jets channel. Auguste Besson. Signal topology Data/Background studies Event display Remarks on RPV decays Do list. SUSY RPV with  122 ’. Final state. Pair production of SUSY particles Decays of the 2 LSPs with  122 ’ coupling.

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Update on Like-sign ee + jets channel

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  1. New Phenomena meeting Update on Like-sign ee + jets channel Auguste Besson • Signal topology • Data/Background studies • Event display • Remarks on RPV decays • Do list SUSY RPV with 122’ New Phenomena, June 27th 2002.

  2. Final state • Pair production of SUSY particles • Decays of the 2 LSPs with 122’ coupling Final State : 2 electrons + 4 jets New Phenomena, June 27th 2002.

  3. Pre-selection (Preselection made by Pavel Demine) • 9.7 pb-1of data (02/01/02→06/01/02) • p10.15.01 used • Bad runs removed (MET,SMT,CFT,…) • 2 EM candidates • pT≥8 GeV/c • HM8 < 20 • em_util corrections Non linearities, Energy corrections, Phi cracks removed • Jets • pT ≥15 GeV/c ;  < 2.6 • Jet Energy correction • R jet-electron > 0.7 • R jet-jet > 1.4 New Phenomena, June 27th 2002.

  4. Triggers • DATA : • EM_HI only : 8.8 pb-1 • SM Background : • Apply approximate trigger efficiency. CEM(1,20) At least 1 electron || < 0.8 • NEXT • Use EM_HI turn-on deduced from data (see Pavel’s talk) Trigger efficiency D0 note 3949 Klute & Quadt pT electron New Phenomena, June 27th 2002.

  5. Standard Background • Inclusive processes (+jets) • Certification quality • Jets :  < 2.6 pT > 15 • tight leptons : HMx8 < 15 • Considered cuts • Sign of leptons • pT leptons • Number of jets • pT jets p10.11 p10.15 New Phenomena, June 27th 2002.

  6. Selection with 1 matching track • 2 tight electrons • pTe1 > 15 GeV • pTe2 > 10 GeV • 1 track match Data : 511 events Bckgd : 394 events Data in black/yellow shaded Background (dashed) Number of electrons New Phenomena, June 27th 2002.

  7. Selection with 2 matching tracks Background (dashed) Data in black/yellow shaded Bckgd: ~20-30% more events in the Z peak Number of electrons • Data : 137 events • Bckgd : 145.7 events Invariant Mass New Phenomena, June 27th 2002.

  8. Et/pT,missing Et, pT el Data in black/yellow shaded Background (dashed) MC Missing Et pT el1 ET over pT Good agreement except for ET/pT New Phenomena, June 27th 2002.

  9. Jets multiplicity pT of jets 1 Data in black/yellow shaded Background (dashed) CDF.PRL (1996) 448 Jet multiplicity for Zee events, pT>15 Jets Multiplicity Higher for MC (pythia) MC problem ? Number of jets New Phenomena, June 27th 2002.

  10. Selected events • el1 pT>15 GeV; el2 pT>10 GeV (tight) • Jets pT>15 GeV Data Only 8 events with like sign-dielectrons Background Cross-section error + statistical error +10% error on luminosity assumed, Good agreement if 2 tracks matched is required. New Phenomena, June 27th 2002.

  11. Background contributions As expected : Mostly Zee(60-130) ~ 90% New Phenomena, June 27th 2002.

  12. Sign assignment error • Selection of 2 tight electrons in the Z peak • pTe1 > 15 GeV • pTe2 > 10 GeV • 2 tracks match • 86 < Mee < 98 • The error depends on pT Approximate rate ~ 4 % To be used for SM Bckgd. Invariant Mass New Phenomena, June 27th 2002.

  13. Studying events with high jet multiplicity :2 leptons + 3 jets, only 1 track match Run 149344; event 7295723 3 jets D Run 2 Preliminary New Phenomena, June 27th 2002.

  14. Studying events with high jet multiplicity :2 opposite sign leptons + 2 jets, not in Z peak Run 151911; event 27000396 D Run 2 Preliminary 2 jets Most probably : Zee event With one electron badly measured, producing overestimated Et miss. New Phenomena, June 27th 2002.

  15. Studying events with high jet multiplicity :2 like sign leptons + 2 jets Run 146452; event 6623841 2 jets D Run 2 Preliminary Most probably : Z + 2jets event Mee = 87.2 GeV New Phenomena, June 27th 2002.

  16. >0 <0 Branching ratios of LSP→e±+2jets • LSP can decay to e± or  + 2 jets 0 is bino-like for  < 0 0 is wino-like for  > 0  < 0 → Br(ejj) ~ 50%  > 0 → Br(ejj) ~ 10% New Phenomena, June 27th 2002.

  17. Direct and indirect decays • Mostly only the LSP decays in RPV Direct decay of Neutralino 2 in RPV small Limit on 122’ Branching ratio RPV Branching ratio RPV Br <3% >0 <0 coupling coupling New Phenomena, June 27th 2002.

  18. Pair production cross-sections vs M1/2 • SUGRA A0 = 0 M0 = 100 tan  = 5  < 0 ±0 Cross-section (pb) squarks Charginos/Neutralinos pairs dominant M1/2 New Phenomena, June 27th 2002.

  19. Pair production cross-sections vs M1/2 • mSUGRA A0 = 0 M0 = 300 tan  = 5, 15  < 0 or > 0 Charginos/Neutralinos pairs dominant Still true in a large range of the parameter space M1/2 New Phenomena, June 27th 2002.

  20. Do list • Background studies: • Tight e± + e± fake • In progress (O.Kouznetsov) • Use sign assignment error on SM background • trigger simulation on background • Understand jets multiplicity (try other MC ?) • Improve selection with new cuts • M͂͂͂͂ee not between 80-100 • Etmiss • Scalar Et, sphericity, etc… • Full simulation signal in progress. • Scan in SUGRA model. New Phenomena, June 27th 2002.

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