Charm antiquark ($\bar{c}$)

The charm antiquark $\bar{c}$ is the antiparticle of the charm quark. It has electric charge $-2e/3$, baryon number $-1/3$ and the opposite charm flavor number, while retaining spin $1/2$ and the same mass. Its color transformation is the conjugate of a quark's.^[ref]

A charm–anticharm pair has zero net charm and can form charmonium. Zero net charm does not imply absence of charm constituents: it states that quark and antiquark flavor numbers cancel. This distinction is useful when balancing conserved flavor numbers at a strong interaction vertex or classifying a meson's minimal valence content.