Pion
The least massive type of subatomic particles made of a quark and an antiquark (called mesons).There are three types of pions, all with a very short lifetime. Two of them carry an electric charge equal to the elementary charge (π+ and π-); they share the same mass and same lifetime, and only differ by the sign of their charge. The lifetime of the neutral pion (π0), which is slightly less massive, is far shorter than the lifetime of the charged pions.