2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/190657We derive expressions for the phase-space of a particle of momentum $p$ decaying into $N$ particles, that are valid for any number of dimensions. These are the imaginary parts of so-called `sunset' diagrams, which we also obtain. The results are given as a series of hypergeometric functions, which terminate for odd dimensions and are also well-suited for deriving the threshold behaviour.12 pages, RevTex. 2 minor algebraic corrections to page 4 after eqns (6) and (8)High Energy Physics - Theorytext