Strangeness

Evaluation of strangeness production has become an important tool in search, discovery, observation and interpretation of quark–gluon plasma (QGP).

[3] Strangeness is an excited state of matter and its decay is governed by CKM mixing.

For all the quark flavour quantum numbers (strangeness, charm, topness and bottomness) the convention is that the flavour charge and the electric charge of a quark have the same sign.

Strangeness was introduced by Murray Gell-Mann,[4] Abraham Pais,[5][6] Tadao Nakano and Kazuhiko Nishijima[7] to explain the fact that certain particles, such as the kaons or the hyperons Σ and Λ, were created easily in particle collisions, yet decayed much more slowly than expected for their large masses and large production cross sections.

Noting that collisions seemed to always produce pairs of these particles, it was postulated that a new conserved quantity, dubbed "strangeness", was preserved during their creation, but not conserved in their decay.

In most cases these decays change the value of the strangeness by one unit.

This doesn't necessarily hold in second-order weak reactions, however, where there are mixes of K0 and K0 mesons.

Here strangeness is conserved and the interaction proceeds via the strong nuclear force.

[9] Nonetheless, in reactions like the decay of the positive kaon: