Strange quark ($s$)

The strange quark $s$ is the second-generation down-type quark, with electric charge $-e/3$, spin $1/2$, baryon number $1/3$ and strangeness $-1$. Its strange antiquark has the opposite additive quantum numbers.^[ref]

The strong interaction can create a strange–antistrange pair without changing total strangeness. A later weak interaction can change net strangeness, allowing a strange hadron to decay into nonstrange products. This separation of production and decay mechanisms makes the strangeness label useful in reconstructing particle reactions. Its sign is a convention for the flavor quantum number, rather than the sign of an additional physical electric charge.

The antiparticle of the strange quark has electric charge $+1/3$ and baryon number $-1/3$.