Coupling vector and pseudoscalar mesons to study baryon resonances

TL;DR

This paper investigates how coupling vector mesons to pseudoscalar meson-baryon systems affects the properties of baryon resonances, revealing strong couplings and potential implications for reaction dynamics.

Contribution

It introduces a framework coupling vector and pseudoscalar mesons to study baryon resonances, highlighting the strong VB channel couplings to known resonances like $ ext{Lambda}(1405)$ and $ ext{Lambda}(1670)$.

Findings

Strong VB coupling to $ ext{Lambda}(1405)$ and $ ext{Lambda}(1670)$

Evidence for double pole structure of $ ext{Sigma}(1480)$

Implications for reactions producing these 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, $\Lambda(1405)$, $\Lambda(1670)$, 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 $PB \rightarrow PB$ and $VB \rightarrow VB$ amplitudes from the t-channel diagrams and the $PB \leftrightarrow VB$ 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 an 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.