Speaker
Description
The direct pair-production of the tau-lepton superpartner, stau, is one of the
most interesting channels to search for SUSY. First of all the stau is with high
probability the lightest of the scalar leptons. Secondly the signature of stau
pair production signal events is one of the most difficult ones, yielding the
'worst' and thus most general scenario for the searches.
The most model-independent limits on the stau mass comes from the LEP experiments. They
exclude a stau with mass below 26.3 GeV for any mixing and any difference between stau and
neutralino masses larger than the tau mass.
The LHC exclusion reach extends to higher masses for large mass differences, but under strong
model assumptions.
Future electron-positron colliders are ideally suited for stau searches: they
will feature increased luminosity and centre-of-mass energy, and improved accelerator,
detector and analysis technologies with respect to previous electron-positron colliders.
With respect to hadron colliders, they will profit from a cleaner environment, from the
initial state being known, and from trigger-less operation of the detectors.
In this contribution, the prospects for discovering stau-pair
production at future e+e- Higgs factories and the resulting detector
requirements will be discussed.
For detector-level simulations, the study takes the ILD detector concept
and ILC parameters at 500 GeV as example. It includes all SM
backgrounds, as well as beam induced backgrounds, as overlay-on-physics
and - for the first time - overlay-only events, and considers the
worst-case scenario for the stau-mixing. It shows that with the chosen
accelerator and detector conditions, SUSY will be discovered if the
NLSP mass is up to just a few GeV below the kinematic limit of the
collider.
Based on these results, expectations for other center-of-mass energies,
luminosities, beam polarisations, beam background and detector
conditions will derived. Among the detector performance criteria,in
particular the role of the hermeticity of the detector, of the tracking
acceptance and of the ability to operate trigger-less will be discussed
and put into perspective of the experimental environment expected at
different Higgs factories.
