Derivation of some kinematical formulas in SUSY decay chains

In this note a few formulas for kinematic edges used in SUSY searches are collected. These kinematical edges are interesting not only for SUSY events but their decay chains will be used as an example. Some assumptions with massless leptons have been made but they should be easily generalizable. In addition this note includes a section with formulas to reconstruct $\tilde \ell_L$ decays at a particular point. Sleptons would only rarely have long decay chains and a reconstruction would require not only knowledge about the masses but also more than 600 fb$^{-1}$ of integrated luminosity.