Does anyone have suggestions on the strategies for a four-body decay's kinematics? I'm just wondering what is out there. Last time I had to calculate something I just did it straightforward, but I know there must be other methods. (Like preferring to work in energies over invariants). I usually base it off of preprint : http://ccdb5fs.kek.jp/cgi-bin/img/allpdf?198311072 [Broken] But are there new strategies? Say for a four-lepton final state. Thanks edit: I should also add, that if you prefer analytic solutions there must be preferred methods. Numerically it probably doesn't matter due to the cuts being easy to implement.