Mass and Spin Measurement with M_T2 and MAOS Momentum

We discuss the M_T2-kink method to determine the masses of both the dark matter WIMP and its mother particle produced at the LHC. We then introduce a new kinematic variable, the M_T2-Assisted-On-Shell (MAOS) momentum, that provides a systematic approximation to the invisible particle momenta in hadron collider events producing a pair of invisible particles, and apply it to certain SUSY processes and their UED equivalents to determine the spin of gluino/KK-gluon and of slepton/KK-lepton. An application of the MAOS momentum to the SM Higgs mass measurement is briefly discussed also.