Same-sign trileptons as a signal of sneutrino lightest supersymmetric particle

Contrary to common expectation, a left-sneutrino can occasionally be the lightest supersymmetric particle. This has important implications in both collider and dark matter studies. We show that same-sign tri-lepton (SS3L) events at the Large Hadron Collider, with any lepton having opposite sign vetoed, distinguish such scenarios, up to gluino masses exceeding 2 TeV. The jets+METjets+MET signal rate is somewhat suppressed in this case, thus enhancing the scope of leptonic signals.