Published on September 29, 2007
News from ~1fb-1 of e+e- dataat Ecm=192-202 GeV: News from ~1fb-1 of e+e- data at Ecm=192-202 GeV Nikos Konstantinidis UC Santa Cruz Outline: Outline New physics in SM processes photons, WW, ZZ… Direct searches Higgs and SUSY The future LEP at Y2K, after LEP? LEP in 1999 - A story of success!: LEP in 1999 - A story of success! 253 pb-1 LEP operator: Not an easy job!: LEP operator: Not an easy job! RF cavities operated at ~<7 MV/m> well above their design gradient (~6MV/m) Cryogenics operated at limit capacity! <Fill time> 2.7 hours 2.1 hours 1.6 hours For what follows...: For what follows... 30 pb-1 at 191.6 GeV 80 pb-1 at 195.5 GeV 85 pb-1 at 199.5 GeV 40 pb-1 at 201.6 GeV 235 pb-1/expt Results very preliminary!!! (presented one day after the end of run) open questions after the ADLO presentations implications of the latest results Limits at 95% C.L. - Discoveries at 5s Emphasis on Final states with photons : Final states with photons Topology SM process New processes Single photon Two acoplanar photons Two coplanar photons Single ISR Double ISR QED t-channel electron exchange Anomalous TGC’s Extra dimensions Extra dimensions Excited leptons Contact interactions SUSY (GMSB) Results with photons: Results with photons Acoplanar photons Single photons 584 obs 592 exp 35 obs 34 exp Slide8: W/Z pair production Experimental precision challenges theory(*) (*) hep-ph/9907436 hep-ph/9909363 Limits on anomalous neutral vector boson couplings and extra dimensions DELPHI eeqq excess: DELPHI eeqq excess mmqq eeqq Mqq (GeV/c2) Mll (GeV/c2) 10 observed / ~1 expected (in range 50-56 GeV/c2) Mqq~MZ …not confirmed by others : …not confirmed by others ALEPH llqq mass spectrum already studied before the DELPHI announcement: No excess! Specific modifications to approach the DELPHI analysis: Still no excess! 50-56 GeV/c2: 3.5 expected 1 observed eeqq mmqq SM Higgs - A new regime : SM Higgs - A new regime New in 1999: - Moving away from MZ - Covering an exciting mass range HZ - Topologies: HZ - Topologies BR (%) 60 17 6 9 eff (%) 40 40 70 30 Bkg’s: ZZ,qq,WW ZZ,WW,qq ZZ,Zee ZZ,WW Handles: b-tagging Acoplanarity lepton-ID tau-ID 4 jet topol. Mmis = MZ + isolation b-tagging b-tagging Mll = MZ ALEPH Higgs Rumors: ALEPH Higgs Rumors Jun Aug Sep Nov Rumors start here… … and end here! Shown to summer conferences ALEPH Higgs Search: ALEPH Higgs Search Cb max = 0.87 ~1 sigma excess Cb: The compatibility with SM background. Contains much more information than a mass plot! Data compatible with SM Excess in data Deficit in data SM Higgs results up to 202 GeV: SM Higgs results up to 202 GeV ADLO: ~109 GeV (Up to 200 GeV only) (~200 pb-1 only) MSSM - Neutral Higgs bosons: Low tanb region slowly covered: ADLO: tanb > ~2 MSSM - Neutral Higgs bosons Beginning of LEP2 MSSM scans show no pathological points ADLO ‘99 Theory ‘99 ADLO: ~90 GeV Charged Higgs: Charged Higgs Hitting the W wall Enough luminosity to explore masses above MW (?) OPAL + DELPHI excess around 90-95 GeV gone… ADLO (189 GeV): 77.3 GeV Slide18: SUSY topologies and backgrounds R-parity conserved: Missing energy + 4 jets 2 jets-lepton 2 leptons 2 jets Signal event properties and backgrounds depend on: large DM small DM Cross section limits: Cross section limits Covering the small DM region: Covering the small DM region The LSP mass limit : The LSP mass limit ~36 GeV Higgs searches may have a significant impact on the LSP mass limit! From chargino kin. threshold Other searches...: Other searches... Invisible Higgs decays, fermiophobic Higgs Squarks/sleptons, GMSB with stau as NLSP Heavy stable particles Excited leptons Deviations from SM in 2-f processes Anomalous TGC’s LEP in Y2K - Ultimate reach: LEP in Y2K - Ultimate reach Standard Model Higgs Sensitive up to ~ (Ecm-MZ) -> 114 GeV/c2 Charginos Sensitive up to ~ Ecm/2 -> 104 GeV/c2 MSSM Higgs h,A close to 95 GeV/c2 charged Higgs: sensitivity above MW 202 GeV : Successful operation in 1999 204 GeV : Pilot run (~10nb-1/expt) in 1999 206 GeV : Seems possible in 2000 (obtained in tests) 208 GeV : Optimistic? (but not out of question...) >210 GeV : forbidden by French law!!! If no Higgs at LEP?: If no Higgs at LEP? If central value of MH stays as is now, strong motivation for both Tevatron and LHC to prepare for the most difficult Higgs hunt: MH ~ 130 GeV/c2 LEP’s last contribution to the Higgs search is the indirect determination of its mass using the most precise W mass to that date! “Ball” passed to Fermilab! Summary: Summary Not too late to reward it with a discovery!!! An outstanding year for LEP concludes a decade of a successful experimental program of leading research!!! 1999: a year of excitement and good results … but negative results!