Applications of Chiral Perturbation Theory: Mass Formulas and the Decay eta --> 3 pi
May, 197444 pages
Published in:
- Phys.Rev.D 10 (1974) 2904
Report number:
- COO-2232B-53
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Abstract: (APS)
Several new results on the breaking of chiral SU(3) × SU(3) are presented within the theoretical framework of chiral perturbation theory. (a) The leading-order corrections to the Gell-Mann-Okubo formula for the baryon octet are shown to be of order ε32, where ε is a chiral symmetry breaking parameter. An explicit exact expression is given for the leading-order corrections, which provides a new development in understanding why this formula works so well. Similarly the corrections to the Gell-Mann-Okubo formula for the ground-state pseudoscalar octet are shown to be of order ε2lnε (including η−η′ mixing). On the basis of these exact results it is argued that SU(3) × SU(3) symmetry is as good as SU(3) symmetry ∼30% except when one considers electromagnetic interactions. (b) We examine the η→3π decay on the assumption that it is regulated by a nonelectromagnetic isospinviolating term of the type ε3u3 with u3 a member of 3¯3⊕33¯. The strength ε3 of this term is related to the experimental rate including all leading-order chiral-symmetry corrections. This estimate of ε3 leads to ΔI=1 hadron level shifts about a factor of 2 or 3 too large, although our estimate of ε3 depends sensitively on the experimental details. (c) Octet enhancement, an exact formalism to describe η−η′ mixing, and other topics are discussed.References(43)
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