CPT theorem has been known to imply the equality of mass and lifetime between particle and antiparticle even if C(charge conjugation) symmetry is violated. However, its mathematical verification is insufficient and limited as it considers only one type of C violation. Here C, not CPT, symmetry will be shown to imply the equality of mass and coupling constants and the lifetime could be the same regardless of C and CPT violation. And we conclude that the equality of mass and lifetime is prerequisite for the CPT theorem to be valid and it is not implied by CPT symmetry. |