1 / 22

The facts: First look to the excess Studies going on … Perspectives for 2000 run

Status report from the LEPSUSYwg: “The stau excess” F Cerutti, G.Ganis, F.Holldorfer, K.Jakobs and M.Maggi. The facts: First look to the excess Studies going on … Perspectives for 2000 run Signal hypothesis Fluctuation hypothesis Possible strategy Conclusions ?!?.

fallon
Download Presentation

The facts: First look to the excess Studies going on … Perspectives for 2000 run

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. Status report from the LEPSUSYwg: “The stau excess”F Cerutti, G.Ganis, F.Holldorfer, K.Jakobs and M.Maggi • The facts: • First look to the excess • Studies going on … • Perspectives for 2000 run • Signal hypothesis • Fluctuation hypothesis • Possible strategy • Conclusions ?!? F.Cerutti

  2. The facts: combined excess • stau ADLO 189-202 GeV combined • Exchanged matrixes in the Mstau-Mchi plane : Cand, Bkg, Eff

  3. The facts: excess probability • Estimator used to quantify the excess

  4. The facts: excess probability

  5. The facts: excess probability • E fraction of point with CLexcess<2% • Gedanken experiments (bkg only) • Pexcess= N(E>Edata)/Ntot =10-3 (6.8% A)

  6. Mstau from xs • Find the stau mass comparingstRvs data excess (Mc<30): • MtR = (86.7 ± 1.4) GeV (Mc~15-35)

  7. The reference point • Take as “reference point” Mt=85 GeV Mc=20 GeV: • Cand = 226 • Bkg = 179.5 • P(Bkg,NNcand) = 5 x 10-4

  8. Compatibility with signal in the reference point : ALEPH only

  9. Bkg composit. and systematics • Background composition in 85-20: • Systematics on bkg: ~2-4% dominated by MC statistics • If we add 4% to bkg in 85-20: P(Bkg,NNcand) = 3 x 10-3 • Gedanken experiment full plane with bkg sys (+1s): Pexcess=N(E>Edata)/Ntot=1.2%

  10. Comparison Data vs Bkg • Decided to exchange more info within ADLO to allow additional checks • For each event (Data, MC Bkg and MC signal) exchange: Pt1 Pt2 Pmiss Weight(bkg) Bin-position, ... • For the 85-20 point check variables [Bkg vs Data] ADL(189-202)O(189) DT=184 MC=146. Excess = 38±14 (2.7 s)

  11. Comparison Data vs Bkg • Emax • Emin • Mtt • Ptmiss • Acollinearity • Emax vs Emin • Mt1 vs Mt2 • Tau ID1 vs Tau ID2

  12. ALEPH: H+ vs stau (B.Fabbro) • H+ vs stau Large-dM (L-dM.OR.S-dM): can bkg can bkg 189 20 15.520 15.5 192-202 36 35.530(46) 21.7(34.2) e(M=85) 38%39% • The two analyses are NOT incompatible • cand=16 bkg=17 dif=-1±4 H+ only • cand=10 bkg=4 dif=6±3 stau only • cand=20 bkg=18 dif=2±4 H+.AND.stau • Warning: 9 events(5 large-dm)selected by stau and NOT by H+ have a NOT identifiedenergetic lepton -> to be checked !

  13. Perspective for y2k run • Patrick performance for LEP y2k

  14. Perspective for y2k run • Studied 18configurations: • 1 22 weeks at 192 GeV • 2 “ 196 GeV • 3 “ 198 GeV • 4 “ 200 GeV • 5 “ 202 GeV • 6 “ 203 GeV • 7 “ 204 GeV • 8 “ 204.6 GeV • 9 “ 205.2 GeV • 10 “ 206 GeV • 11 22 w 206.8 GeV

  15. Perspective for y2k run • 12 22 w MiniRamp 1-step 4-bun. • 13 22 w MR + 24 w extens. MR • 14 22 w + 24 w extens. 200 GeV • 15 Status at LEPC in July MR • 16 MR up to LEPC+200 GeV 22+24 • 17 MR up to LEPC+200 GeV 22+2 • 18 Status before 2000 run • Results for signal hypothesis in the given for three stau masses: 85,87 and 89 GeV (mild dependence from Mc=20 GeV)

  16. Mt=87 GeV

  17. Mt=85 GeV Mt=89 GeV

  18. Significance for Mstau = 89-85 GeV • 1 22 weeks at 192 GeV 3.1-3.9 sigma • 2 “ 196 GeV 3.4-4.3 sigma • 3 “ 198 GeV 3.5-4.3 sigma • 4 “ 200 GeV 3.6-4.3 sigma • 5 “ 202 GeV 3.6-4.2 sigma • 6 “ 203 GeV 3.6-4.1 sigma • 7 “ 204 GeV 3.6-4.0 sigma • 8 “ 204.6 GeV 3.5-4.0 sigma • 9 “ 205.2 GeV 3.5-3.9 sigma • 10 “ 206 GeV 3.1-3.3 sigma • 11 22 w 206.8 GeV 3.1-3.3 sigma • 12 22 w MiniRamp 1-step 3.4-3.8 sigma • 13 22+24 w MR 3.8-4.5 sigma • 14 22+24 w 200 GeV 4.1-5.3 sigma • 15 Status at LEPC in July mr 3.2-3.5 sigma • 16 MR up to LEPC+200 GeV (22+24) 4.1-5.2 sigma • 17 MR up to LEPC+200 GeV (22+2) 3.5-4.2 sigma • 18 Status before 2000 run 2.9 sigma

  19. Perspective for y2k run:No signal hypothesis • Question: can we exclude at 95% CL 85<Mt<89 with next year data alone ? • Answer: YES but for configurations 10, 11, 15 and 17(89 GeV only) ! • 10 Ecm=103 • 11 Elep=103.6 • 15 Status at LEPC with MR • 17 MR up LEPC then 198 GeV

  20. Conclusions ?!? • The facts: • An excess in the ADLO combined LEP data has been found • This excess corresponds to a probability ~10-3 without any bkg systematics • With the bkg systematics included it goes up to ~0.5-1% (not a discovery !) • To be better understood background systematics (A lepton ID) • Y2K run: signal hypothesis: • 4-5 sigma significance still reachable if emphasis toL is given and6 months extension is obtained

  21. Conclusions ?!? • At the July LEPC significance could increase from the actual 2.9 to [3.3-3.5] sigma (assuming a successful MR run) • Significance [3.8-5] sigma could still be reached if, after LEPC, run is optimized for L (run at ~200 GeV) .AND. the 6 months extension is given • Y2K run: no signal hypothesis: • A [85-89] GeV stau mass can be excluded at 95% CL by next year run alone in all the run configurations but the run at the highest energy (103 GeV)

  22. Y2K optimal stau strategy ?!? • Run with MR up to LEPC ~ 120pb-1 than: • Higgs exclusion (Kinematic limit ?) • Stau excess significance (+ or - ?) • If+ indication for stau AND- for H (and c+): switch from MR to optimal stau run (large L at Elep~200) • Final decision on 6 months extensionshould be taken later (and/or as soon as the 4 sigma are reached): August-September ? • Ongoing work: • Careful review of bkg systematics • Provide signal files and fit for Mstau-Mchi (xs plus shapes) • Schedule regular meetings during y2k run

More Related