1. 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 +)

2. The MSSM
tan v2/v1

3. 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 -  tantan t
b 

4. 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) ;
* 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)

5. Backup slides Centre-of-Mass Energy ALEPH DELPHI L3 OPAL
191.6 GeV
195.6 GeV
199.6 GeV
201.6 GeV
205 GeV
206.6 GeV
208.1 GeV

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

7. 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