A strange particle is an elementary particle with a strangeness
quantum number different from zero. Strange particles are members of a large family of
elementary particles carrying the quantum number of
strangeness, including several cases where the quantum number is hidden in a strange/anti-strange pair, for example in the
ϕ meson. The classification of particles, as
mesons and
baryons, follows the
quark/
anti-quark and three quark content respectively.
Murray Gell-Mann recognized the group structure of elementary particle classification introducing the flavour SU(3) and strangeness as a new quantum number.[1][2][3][4][5]