Eightfold way (physics)

In physics, the Eightfold Way is a term coined by American physicist Murray Gell-Mann for a theory organizing subatomic baryons and mesons into octets. The theory was independently proposed by Israeli physicist Yuval Ne'eman.

The name Eightfold Way is an allusion to the Noble Eightfold Path of Buddhism.

In addition to organizing the mesons and spin-1/2 baryons into octets, the principles of the Eightfold Way could also be applied to the spin-3/2 baryons, forming a decuplet. However, one of the particles of this decuplet had never been previously observed. Gell-Mann called this particle the Ω⁻ and predicted in 1962 that it would have a strangeness −3, electric charge −1 and a mass near 1680 MeV/c². In 1964 a particle closely matching these predictions was discovered by a particle accelerator group at Brookhaven, making the Eightfold Way a triumphant success. Gell-Mann went on to receive the 1969 Nobel Prize in physics for his work on the theory of elementary particles.

The Eightfold Way may be understood in modern terms as a consequence of flavor symmetries between various kinds of quarks. Since the strong nuclear force is the same for quarks of any flavor, replacing one flavor of quark with another in a hadron should not alter its mass very much. Mathematically, this replacement may be described by elements of the group SU(3). The octets and other arrangements are representations of this group.

References

• Griffiths, David (1987). Introduction to Elementary Particles. New York: John Wiley & Sons. ISBN 0–471–60386–4.