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Search for MSSM Particles at LEP and Interpretations

Search for MSSM Particles at LEP and Interpretations. Giacomo Sguazzoni CERN –EP Division on behalf of LEP collaborations. Wish list. Primary signal searches Acoplanar leptons (sleptons) Acoplanar jets (squarks) Multi-body + missing energy. Interpretations CMSSM mSUGRA.

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Search for MSSM Particles at LEP and Interpretations

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  1. Search for MSSM Particles at LEP and Interpretations Giacomo Sguazzoni CERN –EP Division on behalf of LEP collaborations

  2. Wish list • Primary signal searches • Acoplanar leptons (sleptons) • Acoplanar jets (squarks) • Multi-body + missing energy • ... • Interpretations • CMSSM • mSUGRA • LEP vs. the future • Tevatron • LHC G.Sguazzoni

  3. Disclaimer • MSSM • R parity conservation • Pair production • LSP stable • (cosmology  neutral and weakly interacting) • …will show LEP SUSY Working Group (preliminary!!! ) combination when available! • …all limits @ 95% Conf. level Time-saving phenomenology intro™ ALEPH DELPHI L3 OPAL G.Sguazzoni

  4. LEP2 Data sample 1999 1998 2000 • Good for searches: • High energy • up to ~209GeV • High luminosity • s200GeV • 10pb-1 @ s208GeV ECM (GeV) 161+172 183 189 192-202 204-209 tot Int.Lumi (pb-1) 25 63 200 254 233 775 1996 1997 /experiment G.Sguazzoni

  5. Acoplanar e, m, t • Missing energy/momentum • Lepton/Tau ID c c c c t • Searching for: • sleptons t c c G.Sguazzoni

  6. …limits stauR s<40-60fb Tau ID M>85.9 GeV/c2 smuonR s<10-30fb M>94.2 GeV/c2 selectronR s<10-30fb Higher expected s M>99.6 GeV/c2 ELEP=183-208GeV Mass Limits DM>10GeV/c2 G.Sguazzoni

  7. Topological variables • E, P / / Acoplanar jets • Searching for: • squarks • b-tagging • +leptons jet c Pmiss jet New! stop 4body decay c • Multi-jets G.Sguazzoni

  8. q=56o q=68o q=56o q=56o Squark limits • similar sensitivity for any decay channel!!! Mc Mc Mc(GeV/c2) MSNEU MSBOT<Mc+mb MSTOP<MSNEU+mb MSTOP<Mc+mb MSTOP<Mc+mc q=0o q=0o q=0o D0 q=0o CDF CDF LEP1 NEW! ADLO ADLO ADLO ALEPH MSTOP MSTOP MSBOT MSTOP(GeV/c2) MSBOT>92GeV/c2 >95GeV/c2 >77GeV/c2 MSTOP>94GeV/c2 DM>10GeV/c2, any q G.Sguazzoni

  9. Stable hadrons • absolute stop mass lower limit • 63 GeV/c2 • (any q, BR, lifetime) MSTOP-MLSP<5GeVlifetime!!!! l~LDET kink/IP l~LDET dE/dx PLB 488 (2000) 234 G.Sguazzoni

  10. / / • gg with E, P Topologies with g(g) c1 s<10-30fb c1 g g • Single g g • Search for • ci>1c1radiative decays • very powerful for not-MSSM scenarios c1 c1 s<40-100fb G.Sguazzoni

  11. Topological variables • E, P • multi-body / / 2/4 fermions+(EMISS,PMISS) • searches for: • charginos • neutralinos G.Sguazzoni

  12. …example of s limits • high m0 (heavy sleptons) s100-300fb s100-200fb OPAL Preliminary OPAL Preliminary G.Sguazzoni

  13. ...extending the horizon • …other sparticles mass limits • Phenomenology: • new topologies • loop-holes? cMSSM mSUGRA • LSP (not directly observable!) mass limits  SUSY grinder reasonable model warranty …all results are grinder-dependent!!! G.Sguazzoni

  14. C-MSSM • M1=5/3tan2qWM2~0.5M2 • m0 for sfermions • no mixing • tanb, m Playing with CMSSM m0= 500GeV/c2 tanb=2 • small m0: •smaller s(c+c-) •light sleptons!!! 109 kin. limit M(c)[GeV/c2] 103 97 91 cicj 102 103 m0=75GeV/c2 tanb=2 M2 c+c- sleptons LEP1 M2 [GeV/c2] M2 [GeV/c2] m [GeV/c2] m [GeV/c2] small m0 large m0 G.Sguazzoni

  15. (m,M2)Mass limits M(c)=100GeV/c2 • MGAUGINOS(m,M2) •  mass limits M(c)=40GeV/c2 m m0>500GeV/c2 M(c)[GeV/c2] any m0 39.4GeV/c2 93.9GeV/c2 tanb tanb lightest neutralino (LSP) lightest chargino G.Sguazzoni

  16. The MSSM Higgs role m0=75GeV/c2 tanb=2 • MSSM Higgs limit small M2 exclusionsmall tanb exclusion ADLO Higgs m0<1TeV/c2 MTOP=175GeV/c2 Higgs charginos (large m0) M2 [GeV/c2] Higgs m [GeV/c2] in the corridor sleptons • Radiative corrections on the higgs mass!! MLSP>45.6GeV/c2 1 2 5 10 tanb G.Sguazzoni

  17. 3rd family mixing M(c)[GeV/c2] • Stau mixing • chargino “holes” • Robusteness checks: • mixing in sbottom, stop and stau sector (At=At=Ab=0) • only stau mixing any m0 INVISIBLE! mixing tanb tanb=35 m=-1000GeV/c2 M(c)[GeV/c2] charginos selectrons hole driven selections G.Sguazzoni

  18. ...absolute selectron mass limit • selectrons/charginos • search for to cover small vs.c DM Higgs c1c3 + hole-driven selections chargino 2B-3B corridor invisible! G.Sguazzoni

  19. ADLO preliminary mSUGRA m1/2 [GeV/c2] A0=0, MTOP=175GeV/c2 • mSUGRA • m1/2 • m0 • A0 • tanb • sign(m) • more constrained model • complementary benchmark!!! • M(c)53-60GeV/c2 (A0=0) • A0 scan!!! • ~10GeV/c2 weaker limits higgs m1/2 [GeV/c2] m1/2 [GeV/c2] tanb=10 m<0 tanb=40 m<0 Theory excluded Heavy Stable Staus neutralino-stau cascade m1/2 [GeV/c2] A0=0 A0=0 sleptons any A0 charginos m0[GeV/c2] LEP1 m0[GeV/c2] m0[GeV/c2] G.Sguazzoni

  20. SUSY paper? • Nice SUSY paper, will be ready for the WC* • read it! …in your relaxed moments. *Winter Conferences G.Sguazzoni

  21. Heavy Stable Staus Neutralino-stau cascade higgs Fermilab Theory excluded LEP1 The LEP legacy mSUGRA benchmark • M(SPARTICLES)  abouts/2 • high energy/luminosity • DM0 • clean environment!!! m1/2 [GeV/c2] charginos m0[GeV/c2] G.Sguazzoni

  22. Semileptonic c candidate • (26<DM<31 GeV/c2) • ECM=195.6, run #50140, evt #18802 • E(tot)=45.5GeV, M(tot)=35.8GeV/c2 • E12=0 (no small angle activity) • M(miss)=147.6GeV/c2 • P(miss)=28.1GeV/c, PT(miss)=20.7GeV/c Conclusion • SUSY search @ LEP • hunting for events not compatible with SM!!! • not trivial experimental task • MC simulation/detector effects/unusual topologies P(m)=8.52GeV/c M(hadr)=16.0GeV/c2 G.Sguazzoni

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