The renormalised form factors for pseudoscalar meson-baryon coupling are computed in chiral colour dielectric model. This has been done by rearranging the Lippmann-Schwinger series for the meson baryon scattering matrix so that it can be expressed as a baryon pole term with renormalized form factors and baryon masses and the rest of the terms which arise from the crossed diagrams. Thus we are able to obtain an integral equation for the renormalized meson-baryon form factors in terms of the bare form factors as well as an expression for the meson self energy. This integral equation is solved and renormalized meson baryon form factors and renormalized baryon masses are computed. The parameters of the model are adjusted to obtain a best fit to the physical baryon masses. The calculations show that the renormalized form factors are energy-dependent and differ from the bare form factors primarily at momentum transfers smaller than 1 GeV. At nucleon mass, the change in the form factors is about 10% at zero momentum transfer. The computed form factors are soft with the equivalent monopole cut-off mass of about 500 MeV. The renormalized coupling constants are obtained by comparing the chiral colour dielectric model interaction Hamiltonian with the standard form of meson-nucleon interaction Hamiltonian. The ratio of ∆N π and N N π coupling constants is found to be about 2.15. This value is very close to the experimental value.PACS numbers: 12.39. Ki, 12.39.Fe, 13.75.Gx
I. INTRODUCTIONThe meson-baryon form factors are interesting and useful quantities for several reasons. For one thing, we expect the form factors to have some bearing on the underlying structure of the hadrons. For example, in perturbative chiral quark models [1] the pion-baryon form factors are directly related to the quark wavefunctions in baryons. Form factors are essential in the effective models of meson-baryon interactions since hadrons, after all, are not point particles. One also needs these form factors for a consistant description of nuclear phenomena. The meson exchange nucleon-nucleon potentials include phenomenological vertex form factors which are presumably related to the structure of hadrons. Form factors are also needed in computation of photo-and electro-production of baryon resonances since, in principle, the photon can couple to the virtual charged meson cloud in a baryon. Another technical reason for introducing the form factors is that the effective meson-baryon interaction models are, generally, not renormalizable and the form factors provide the needed cut-off functions.Usually, the form factors employed in the meson-baryon interaction models are of monopole type ( ∼ 1 1−k 2 /Λ 2 ) with k 2 being the four momentum carried by the meson. It must be noted that the monopole form is, as such, purely phenomenological and is possibly not related to the underlying structure of the hadrons.The form factors used in earlier calculations [2] were 'hard' with the cut-off parameters Λ ≥ 1GeV . There are, however, recent calculations [3] which indi...