Coupling vector and pseudoscalar mesons to study baryon resonances

Abstract

A study of meson-baryon systems with total strangeness -1 is made within a framework based on the chiral and hidden local symmetries. These systems consist of octet baryons, pseudoscalar and vector mesons. The pseudoscalar meson-baryon (PB) dynamics has been earlier found determinant for the existence of some strangeness -1 resonances, for example, Λ(1405), Λ(1670), etc. The motivation of the present work is to study the effect of coupling the closed vector meson-baryon (VB) channels to these resonances. To do this, we obtain the PB→PB and VB→VB amplitudes from the t-channel diagrams and the PB VB amplitudes are calculated using the Kroll-Ruddermann term where, considering the vector meson dominance phenomena, the photon is replaced by a vector meson. The calculations done within this formalism reveal a very strong coupling of the VB channels to the Λ(1405) and Λ(1670). In the isospin 1 case, we find evidence for a double pole structure of the Σ(1480) which, like the isospin 0 resonances, is also found to couple strongly to the VB channels. The strong coupling of these low-lying resonances to the VB channels can have important implications on certain reactions producing them. © 2011 American Physical Society.