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DELPHI Status

LEPC July 2000. DELPHI Status. Or... Should we extend the run?. Talk Overview. Data taking efficiency and Detector performance Standard model results Searches Supersymmetry Exotica Higgs (& ZZ production!) Conclusions. Performance of DELPHI. Efficiency good, average 93.3%

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DELPHI Status

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  1. LEPC July 2000 DELPHI Status Or... Should we extend the run? W.Murray

  2. Talk Overview • Data taking efficiency and Detector performance • Standard model results • Searches • Supersymmetry • Exotica • Higgs (& ZZ production!) • Conclusions W.Murray

  3. Performance of DELPHI • Efficiency good, average 93.3% • 112.4pb-1 recorded on 20th July • Includes 2.2pb-1 recorded outside declared physics • Congratulations to the pit team W.Murray

  4. TPC Voltage problems • HV problems: • wire slack in sector 6 of 12 • Each trip requires new working point, • ~10 Trips so far • We ran OK for 1 month • Sense wire voltage now reduced from 1435V to 1410V W.Murray

  5. TPC sector 6 • 1/12 running at reduced voltage, gain 40% • Some compensation with shaper settings • DeDx distorted • Z0 run shows efficiency OK • TPC experts suffering more than the data so far Current running W.Murray

  6. VD performance • No new problems in vertex detector • Resolution as good as ever • 10-20mm motion being tracked. • We welcome the Z0’s in September W.Murray

  7. S/ distribution L=87.75pb-1 • qq centre of mass energy/ECM, estimated from jet angles • Agreement with PYTHIA 6125 W.Murray

  8. Two Fermion Production W.Murray

  9. B tagging cross-check Light quarks • Z resonance data well described • Semileptonic WW sample also OK b quarks Non-WW W.Murray

  10. Rb measurement Acts as a check on high-energy data Agrees with Zfitter Y2K W.Murray

  11. W mass Measurement 4 jets qqmn Excellent qqen qqtn W.Murray

  12. WW cross-section Channel details: W.Murray

  13. Searches • SUSY- aperitif • Exotica - entrée • Higgs - dessert W.Murray

  14. Single and acoplanar photons W.Murray

  15. Search for c01c02 and c01c03 94.2pb-1 Model independent limits ee:27.7 exp, 26 obs. qq:29.1 exp, 24 obs. mm:23.0 exp, 28 obs. W.Murray

  16. Search for c+ production Topolgies studied: lnqq, lnln, qqqq & radiative tan b >= 1 W.Murray

  17. Search for c+ production Charginos excluded to kinematic limit Mc+>102.2GeV/c2 for dM>10GeV/c2 Not allowed with tanb>=1 W.Murray

  18. LSP mass limit Using c0 and c+ limits up to 2000, DELPHI can exclude LSP below 38.2GeV/c2 Limit at tan b=1, and assuming GUT gauge mass relation. If Higgs 0.8 - 2.0 tan b exclusion applied, we get: 49GeV/c2tan b above 2.0 42GeV/c2tan b below 0.8 - Assumes mt=175GeV/c2 and m0 < 1TeV W.Murray

  19. Squark searches L = 91.4pb-1 DM>15GeV/c2 100%Br. W.Murray

  20. Search for sleptons 93.7pb-1 m=-200 tan b = 1.5 m=-200 tan b = 1.5 Assume ll inaccessible Observed Expected For DM>5GeV/c2 W.Murray

  21. Stau status • Stau results at Moriond interesting 93.7pb-1 @205: m=-200 tan b = 1.5 mt > 68GeV/c2 See Alberto DeMin’s talk W.Murray

  22. GMSB t searches Limit on GMSB at least SUGRA level W.Murray

  23. RPV UDD c01 and c+1 Direct c1 to qqq Indirect c1 to qqqqq Mc+1>102GeV/c2 Mc01>37.5GeV/c2 101.7pb-1 W.Murray

  24. Exotica Technicolour Contact Interactions Flavour changing neutral currents Excited leptons Composit - ness W.Murray

  25. e+e- to gg Data corrected to Born level Limits, combined with other data: L+>342GeV L->319GeV e*>323GeV for l=1 W.Murray

  26. Excited leptons • Nice Candidate for mm* production • m* decay to mg Eg=103GeV, pm=103GeV,0.175GeV W.Murray

  27. Excited leptons L=90.2pb-1 • No sign of a significant excess • Limits for f=f/ and f=-f/ • e* also combined with gg study W.Murray

  28. Technicolo(u)r • Similar to Hqq; different mass pairing & 5C fit • Small excess, nothing striking 100.7pb-1 W.Murray

  29. rT, pT limits Combine: • Couplings depend upon ND, number of doublets • Contours give exclusion for specific ND, solid for all ND For any ND W.Murray

  30. FCNC Single top search • Gives limits on Kg, Kz W.Murray

  31. Higgs searches The main goal of the 2000 run Invisible, Fermophobic Charged ZZ production Standard Model MSSM hA See Alex Read’s talk W.Murray

  32. Invisible Higgs ee qq MH>104.3GeV/c2 107.0 expected Assuming H to invisible 100% mm tt W.Murray

  33. Fermiophobic Higgs to gg 100% L=102pb-1 MH>112GeV/c2 For 100% Br to gg MH>97GeV/c2 For SM Br to gg SM Br W.Murray

  34. ZZ production ZZ to llqq Good description of data ZZ to bbqq Small excess of events W.Murray

  35. ZZ Cross-section L= 92.0-96.9pb-1(channel dependent) • 2 ECM bins: • 204.9GeV (67%) • 206.8GeV (33%) 1.06pb predicted W.Murray

  36. H+H- results 74pb-1 analysed W.Murray

  37. Hll search • 1 candidate in mm, compatible with ZZ • no good candidates in ee Hmm W.Murray

  38. Searches with t’s • Consistent with expectations W.Murray

  39. Hnn channel • Sensitive to high-mass due to WW fusion • Slight deficit of candidates • Consistent with background • Final event has high mass! W.Murray

  40. Hnn candidate • Mass 111GeV/c2 • B tagged rather strongly • A reasonable candidate • possibly qqgg W.Murray

  41. Hqq search • Some excess seen • No Golden candidate • Several bronze • Events peak around 107GeV/c2 W.Murray

  42. Hqq candidate • Mass estimate 105.5GeV/c2 • Two b-tagged jets • A reasonable candidate W.Murray

  43. HZ Mass distribution • Some excess at high mass • But partially compensated by 1999 data MH>109.0GeV/c2 (109.2 expected) W.Murray

  44. hA search bbbb search • Small excess in bbbb channel. • Correlated with ZZ, HZ, Technicolour • Not very significant W.Murray

  45. MSSM Higgs limits Since 1999: • gain of 1.2 GeV in expected limits • loss of 0.5-1 GeV in observed due to the excess in 4b's • tan b between 0.8 and 2.0 is excluded in the pessimistic ‘mh-max’ scenario for mtop=175 • tan b range is 0.6 to 4.2 in the ‘no mixing’ scenario W.Murray

  46. Summary • DELPHI performance is good and well understood • Standard model physics processes normal • No significant signals observed Our thanks to all the LEP team W.Murray

  47. Running Request • To accumulate, as soon as possible, 10pb-1 at the highest possible energy. Presently this seems to be feasible running with the 2*2 scheme. • In September evaluate the possibility to achieve a three sigma Higgs discovery and continue to run until it is excluded that it can be reached before Christmas. Depending upon the conclusion: • Use the reserve weeks to possibly run at higher energy by going to negative frequency shift (possibly compromising the detector backgrounds) and thus gaining 500MeV ECM • Support a dedicated run at the W mass threshold in order to provide a competitive and independent measurement of the mass of the W. This run should aim to collect 200pb-1 before Christmas. W.Murray

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