We investigate helicity amplitudes (HAs) of A→BC-type decays for arbitrary spin towards the kinematic endpoint. show that HAs are proportional to product Clebsch-Gordan coefficients (CGC) and velocity a non-negative power. The latter can be zero in which case HA is non-vanishing at At endpoint explicit breaking rotational symmetry, through external momenta, restored findings interpreted as spec...

The Endpoint Theorem links the existence of a sequence (curve), without accumulation points, in manifold to an open embedding that so image given (curve) has unique endpoint. It plays fundamental role theory Abstract Boundary as it implies there is always boundary point represent endpoint such sequences and curves. will be interest researchers analysing specific spacetimes shows how construct c...