Composite Model of Σ
Abstract
A composite model of Σ as a bound state of Λπ and NK̄ is developed in terms of dispersion relations for form factors and an approximate BetheSalpeter equation. The effective coupling constants of Σ to its constituents are predicted to be 8.7<~g_{Σ0,Λπ0}<~10.7 and 6.4<~g_{Σ0pK}<~7.9 for the range 5.0<~g_{ΛpK}<~13.5. The relative sign of g_{Σ0Λπ0} and g_{Σ0pK} is found to be opposite to the relative sign of g_{ppπ0} and g_{ΛpK}. The model is further applied to a calculation of the onshell electromagnetic form factors of the ΣΛ system. Under the assumption of ρ dominance of the kaon isovector electromagnetic form factor, the ΣΛ transition moment is determined to be G_{2} (O)=g_{ΛpK }g_{Σ0pK }0.9×10^{2} nuclear magnetons, whereas the form factor which would vanish in the limit of equal Σ^{0} and Λ masses is two orders of magnitude smaller than the transition moment.
 Publication:

Physical Review
 Pub Date:
 December 1967
 DOI:
 10.1103/PhysRev.164.1868
 Bibcode:
 1967PhRv..164.1868M