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, $\Lambda (1405)$, $\Lambda (1670)$, 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 $\mathrm{PB}\to \mathrm{PB}$ and $\mathrm{VB}\to \mathrm{VB}$ amplitudes from the $t$-channel diagrams and the $\mathrm{PB}\leftrightarrow \mathrm{VB}$ 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 $\Lambda (1405)$ and $\Lambda (1670)$. In the isospin 1 case, we find evidence for a double pole structure of the $\Sigma (1480)$ 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.

• Received 11 July 2011

DOI:https://doi.org/10.1103/PhysRevD.84.094018