Pseudoscalar- and vector-baryon coupled channel dynamics

por Kanchan Khemchandani (RCNP Osaka (Japan))

lunes 12 dic. 2011 16:00 → 17:00 Europe/Madrid

Sala Seminarios IFIC (Edf. Institutos de Investigación)

Very recently, we have studied vector meson-baryon (VB) systems with the motivation of finding dynamical generation of resonances. In our formalism, the leading order contributions to the scattering equations have been obtained from a sum of diagrammes corresponding to a vector meson exchange in the t-channel, an octet baryon exchange in s-, u-channels and a contact interaction originating from the hidden local symmetry Lagrangian. We find the contribution from all these sources, except the s-channel, to be important. The amplitudes obtained by solving the coupled channel Bethe Salpeter equations for the systems with total strangeness zero, show generation of one isospin 3/2, spin1/2 resonance and three isospin 1/2 resonances: two with spin 3/2 and one with spin 1/2. We identify these resonances with Delta (1900) S31, N*(2080) D13, N*(1700) D13, and N*(2090) S11, respectively. We have further extended our study by including pseudoscalar meson-baryon (PB) systems to VB as coupled channels. 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 low-lying resonances like Lambda(1405) and Lambda(1670). The strong coupling of these low-lying resonances to the VB channels can have important implications on certain reactions producing them. In addition to this, we find that the effect of coupling the higher mass states to lighter, open channels is not restricted to increasing the width of those states, it can be far more strong.