SUSY at LEP2 (third generation and ewinos) LEP2, data What were we searching for? What have we learned from not finding anything.. MSSM with neutralino LSP MSSM + 4 more constraints "mSUGRA" or " CMSSM" MSSM + (1 -2) more constraints (MSSM +)
The MSSM tan v2/v1
Mass relations in MSSM+ Gauge unification and ..... Sfermion unification Gauginos and squarks are related now, we can use charginos to set a limit on squarks and sleptons, and sleptons to set limits on charginos Mixing -> mass splitting for stop and , sbottom and stau A - /tan , A - tantan t b
Backup * ALEPH Collaboration, "Search for scalar quarks in e+e- collisions at sqrt(s) up to 209 GeV", Phys. Lett. B537 (2002) 5-20; * DELPHI Collaboration, " Searches for supersymmetric particles in e+e- collisions up to 208 GeV and interpretation o f the results within the MSSM", Eur. Phys. J. C31 (2003) 421-479; * L3 Collaboration, "Search for Scalar Leptons and Scalar Quarks at LEP", Phys. Lett. B580 (2004) 37-49; * OPAL Collaboration, "Search for Scalar Top and Scalar Bottom Quarks at LEP" Phys. Lett. B545 (2002) 272-284.
Backup slides Centre-of-Mass Energy ALEPH DELPHI L3 OPAL 191.6 GeV 29.92 25.85 29.20 28.42 195.6 GeV 79.83 76.42 81.40 70.56 199.6 GeV 86.29 83.37 73.50 72.39 201.6 GeV 42.01 40.64 15.10 36.52 205 GeV 75.29 78.08 68.95 81.07 206.6 GeV 122.56 139.10 126.46 126.75 208.1 GeV 9.93 7.28 8.54 8.6
e e mass of the selectron neutralino mass Searches for sleptons e R,L l Produced in the same way as leptons. x-section depends on mass and "handness". For selectron t-channel diagram introduces model dependence due to the neutralino mass and coupling. To be conservative we consider usually right-handed sleptons-smaller coupling e R,L / l e e R,L R,L low visibility of the final state if selectron mass close to the neutralino mass-> small e e large WW with W->e background mass of the selectron neutralino mass
Background and signal x-sections Background depends on M(SP)-M(LSP) two-photon for low M, four-fermion for high M "2 photon" Signal x-sections similar to the corresponding SM x-sections, due to same couplings WW Wino Wino ZZ Zino Zino (if selectron light) Higgsino Zino