Mixing of 1/2 − Octets under Su(3) Symmetry

The hypothesis of the approximate SU(3) symmetry of strong interactions proposed by Gell-Mann and Ne’eman 1,2,3 has been proved quite successful and fruitful in the classification of elementary particles. In this classification scheme, one can group the experimentally known strongly interacting particles with the same quantum numbers of spin and parity into various irreducible representations of the SU(3) group 4. The assignment of baryons and mesons to definite SU(3) multiplets seems to be very satisfactory for the 1/2, 3/2 baryons and 0, 1 mesons. It also seems to be satisfactory for the particles with spin-parity 3/2, 5/2, 7/2, 5/2, 7/2 and 2, but poor for 1/2 and 1 hadrons. It has been speculated that the mixing between multiplets might be useful for the interpretation to assign these particles to SU(3) multiplets 5. Recently, Guzey and Polyakov reviewed the spectrum of all baryons with mass less than approximately 2000-2200MeV and catalogued them into twenty-one SU(3) multiplets 6. That work can be viewed as an attempt to update Ref. 4. In their paper, the masses for (N, Λ, Σ, Ξ) members of an octet are listed in a parenthesis. They introduced the mixing of the octet (8, 1/2)=(1535, 1670, 1560, 1620-1725) with the singlet (1, 1/2)=Λ(1405). It is noticed that the small ΓΛ(1670)→NK forces