ϵ-meson coupling constants and scale invariance breaking
1972; Elsevier BV; Volume: 38; Issue: 1 Linguagem: Inglês
10.1016/0550-3213(72)90346-x
ISSN1873-1562
Autores Tópico(s)Particle physics theoretical and experimental studies
ResumoA general method for obtaining ratios of coupling constants (defined by pole residues) in a way which is completely free of resonance/background separation troubles is devised and applied to the ϵ-meson. Huge discrepancies between previous determinations are shown to arise (i) from inherent ambiguities in the methods used, (ii) from lack of knowledge about the ϵ-pole position and (ii) from the well-known up-down ambiguity in the isospin-0 s-wave ππ phase shift δoo. Taking as input πN phase shifts, available information on δoo and including all possible uncertainties we find for down-up or up-up δoo: gϵNNgϵππ = (6 ± 3) μ−1, and for down-down or up-down δ00: gϵNNgϵππ = (1.8 ± 0.5) μ−1. The precise validity of the scale invariance breaking prediction (gϵNN/gϵππ). mϵ22M = 1 is fulfilled in some theoretical ππ models having Γϵ ≈ mϵ ≈ 500 MeV and δoo of up-down type, but is excluded if δoo is down-up or up-up.
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