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A combination of three u, d or s-quarks with a total spin of 3/2 form the so-called baryon decuplet. The lower six are hyperons.

In particle physics, a hyperon is any subatomic particle which is a baryon (and hence a hadron and a fermion) with non-zero strangeness, but with zero charm and zero bottomness. Every hyperon contains one or more strange quarks, with the rest up and down quarks. Thus, suu, sud, sdd, ssu, ssd, sss.

Properties and behavior of hyperons

All hyperons are fermions. That is, they have half-integer spin and obey Fermi-Dirac statistics. They all interact via the strong nuclear force, making them types of hadron. They are composed of three light quarks, at least one of which is a strange quark, which makes them effectively strange baryons. Hyperons decay, directly or indirectly, into a proton or neutron and one or more mesons in 10−10 to 10−8 seconds. If they decay into a neutron, this may further decay into a proton. They are classified through the quark model.

The Ω has strangeness −3, so it takes multiple flavor-changing weak decays for it to decay into a proton or neutron. One such three-step decay was observed in a cosmic ray experiment, but it was not until other Ω particles were produced and observed using particle accelerators that Murray Gell-Mann's SU(3) model (sometimes called the Eightfold Way) was considered confirmed.

Hyperon research

The first research into hyperons happened in the 1950s, and spurred physicists on to the creation of an organized classification of particles. Today, research in this area is carried out on data taken at many facilities around the world, including CERN, Fermilab, SLAC, JLAB, Brookhaven National Laboratory, KEK, and others. Physics topics include searches for CP violation, measurements of spin, studies of excited states (commonly referred to as spectroscopy), and hunts for exotic states such as pentaquarks and dibaryons.

See also

* Hypernucleus

* List of particles

Physics Encyclopedia

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