Lifetime of Polarized Fermions in Flight

Based on the parity violation in the standard model, we study the dependence of the lifetime on the helicity of an initial-state fermion in weak interactions. It is pointed out that if initial fermions in decays are longitudinally polarized, then the lifetime of right-handed polarized fermions is greater than that of left-handed polarized fermions in flight with the same speed in any one of inertial systems.