^ Makeup inexact due to non-zero quark masses. ^ PDG reports the resonance width (Γ). Here the conversion τ = ħ ⁄ Γ is given instead. ^ Strong eigenstate. No definite lifetime (see kaon notes below) ^ The mass of the K L and K S are given as that of the K. However, it is known that a difference between the masses of the K L and K S on the order of 2.2 × 10 MeV/ c exists. ^ Weak eigenstate. Makeup is missing small CP–violating term (see notes on neutral kaons below).