Considering the cascade decay D → cC → cbB → cbaA in which D,C,B,A aremassive particles and c, b, a are massless particles, we determine for the shape of thedistribution of the invariant mass of the three massless particles mabc for the sub-setof decays in which the invariant mass mab of the last two particles in the chain is (optionally)constrained to lie inside an arbitrary interval, mab ∈ [mcut minab ,mcut maxab ].An example of an experimentally important distribution of this kind is the “mqllthreshold” – which is the distribution of the combined invariant mass of the visiblestandard model particles radiated from the hypothesised decay of a squark tothe lightest neutralino via successive two body decay,: ˜q → q ˜ 02→ ql˜l → qll ˜ 01, inwhich the experimenter requires additionally that mll be greater than mmaxll /√2.The location of the “foot” of this distribution is often used to constrain sparticlemass scales. The new results presented here permit the location of this foot to bebetter understood as the shape of the distribution is derived. The effects of varyingthe position of the mll cut(s) may now be seen more easily.
展开▼
