2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/99713The fermion lifetime was usually calculated in terms of spin states. However, after comparing spin states with helicity states and chirality states, it is pointed out that a spin state is helicity degenerate, and so it can not be used for discussion of the dependence of lifetime on the polarization of an initial-state fermion. Using helicity states, we calculate the lifetime of polarized muons. The result shows that the lifetime of right-handed polarized muons is always greater than that of left-handed polarized muons with the same speed in flight.12 pages, no figures, LatexHigh Energy Physics - Phenomenologytext