Strangeness production
Strangeness production is a signature and a diagnostic tool of quark–gluon plasma (or QGP) formation and properties. Unlike up and down quarks, from which everyday matter is made, strange quarks are formed in pair-production processes in collisions between constituents of the plasma. The dominant mechanism of production involves gluons only present when matter has become a quark–gluon plasma. When quark–gluon plasma disassembles into hadrons in a breakup process, the high availability of strange antiquarks helps to produce antimatter containing multiple strange quarks, which is otherwise rarely made. Similar considerations are at present made for the heavier charm flavor, which is made at the beginning of the collision process in the first interactions and is only abundant in the high-energy environments of CERN's Large Hadron Collider.
The majority of matter in the universe is found in atomic nuclei, which are made of neutrons and protons. These neutrons and protons are made up of smaller particles called quarks. For every type of matter particle there is a corresponding antiparticle with the same mass and the opposite charge. It is hypothesized that during the first few instants of the universe, it was composed of almost equal amounts of matter and antimatter, and thus contained nearly equal number of quarks and antiquarks. Once the universe expanded and cooled to a critical temperature of approximately 2×1012 K, quarks combined into normal matter and antimatter. Antimatter annihilated with matter up to the small initial asymmetry of about one part in five billion, leaving the matter around us. Free and separate individual quarks and antiquarks have never been observed in experiments—quarks and antiquarks are always found in groups of three (baryons), or bound in quark–antiquark pairs (mesons).
...
Wikipedia