  We propose a new model-independent technique for mass measurements in missing
energy events at hadron colliders. We illustrate our method with the most
challenging case of a short, single-step decay chain. We consider inclusive
same-sign chargino pair production in supersymmetry, followed by leptonic
decays to sneutrinos. We introduce two one-dimensional decompositions of the
Cambridge MT2 variable: MT2_\parallel and MT2_\perp, on the direction of the
upstream transverse momentum PT and the direction orthogonal to it,
respectively. We show that the sneutrino mass can be measured directly by
minimizing the number of events N in which MT2 exceeds a certain threshold,
conveniently measured from the endpoint MT2^max_\perp.
