We extend the range of possible applications of MT2 type analyses to decay
chains with multiple invisible particles, as well as to asymmetric event
topologies with different parent and/or different children particles. We
advocate two possible approaches. In the first, we introduce suitably defined
3+1-dimensional analogues of the MT2 variable, which take into account all
relevant on-shell kinematic constraints in a given event topology. The second
approach utilizes the conventional MT2 variable, but its kinematic endpoint is
suitably reinterpreted on a case by case basis, depending on the specific event
topology at hand. We provide the general prescription for this
reinterpretation, including the formulas relating the measured MT2 endpoint (as
a function of the test masses of all the invisible particles) to the underlying
physical mass spectrum. We also provide analytical formulas for the shape of
the differential distribution of the doubly projected MT2(perp) variable for
the ten possible event topologies with one visible particle and up to two
invisible particles per decay chain. We illustrate our results with the example
of leptonic chargino decays, (chargino to lepton, neutrino and LSP) in
supersymmetry.Comment: 36 pages, 9 figures, Preprint typeset in JHEP styl