Λ and Σ resonances coupled to vector and pseudoscalar mesons

The vector and pseudoscalar meson–baryon systems have been studied in a coupled channel formalism recently, which has lead to findings of some important results. The formalism consists of obtaining a detailed vector meson–baryon interaction originating from the s-, t-, u-channel diagrams and a contact interaction, all derived from the Lagrangian invariant under the gauge of the hidden local symmetry (HLS). We find the contributions from all the diagrams (except s-channel) to be important, contrary to the systems involving light Goldstone bosons where Weinberg–Tomozawa interaction gives the dominant contribution. Further, the transitions between the pseudoscalar meson–baryon (PB) and vector meson–baryon (VB) channels is obtained consistently by extending the Kroll–Ruderman theorem by replacing the photon by a vector meson, assuming the vector meson dominance. We find that the low-lying resonances couple strongly to VB channels. This information can be very useful in studying processes like photoproduction of low-lying resonances. Further, we find dynamical generation of new states in PB–VB coupled systems which can be related to the known resonances: image, image, image and image.