Study of late decaying charged particles at future colliders

Abstract

In models where the gravitino is the lightest supersymmetric particle, the next-to-lightest supersymmetric particle (NLSP) is long-lived. We consider an important charged NLSP candidate, the scalar tau $\stackrel{\texttildelow{}}{\ensuremath{\tau}}$. Slow charged NLSPs may be produced at future colliders and they may be stopped in a massive stopper which simultaneously serves as a detector for the NLSP and its decay products. We found the number of events at a 1 kton to $\mathrm{O}(10) \mathrm{k}\mathrm{t}\mathrm{o}\mathrm{n}$ detector could be significant enough to study the NLSP decays with lifetime shorter than ${10}^{10}\mathrm{sec}$ at the LHC. The performance of existing 1 kton detectors may be good enough to do such studies at the LHC, if they can be placed close to the ATLAS/CMS detectors. At a future ${e}^{\ensuremath{-}}{e}^{\ensuremath{-}}$ collider, scalar electrons ${\stackrel{\texttildelow{}}{e}}^{\ensuremath{-}}$'s are copiously produced. Slow NLSPs may be produced from the ${\stackrel{\texttildelow{}}{e}}^{\ensuremath{-}}$ decay. The number of stopped NLSPs at a future linear collider could be large enough to study rare decay modes of the NLSP.