Measuring tau-polarisation in Neutralino2 decays at the LHC

Understand

We show how the sum of the two average tau polarisations in the decay chain chi20 -> stau1 tau -> tau tau chi10 in minimal supersymmetry with conserved R-parity can be measured at the LHC.

• This is accomplished by exploiting the polarisation dependence of the visible di-tau mass spectrum.
• Such a measurement provides information on the couplings of the involved SUSY particles and allows a more precise determination of the di-tau mass endpoint.
• If different tau decay modes can be distinguished, the polarisation and endpoint measurement can be improved even further.