K. P. Khemchandani

Coupling vector and pseudoscalar mesons to study baryon resonances

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{yields}PB and VB{yields}VB amplitudes from the t-channel diagrams and the PB{r_reversible}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.

Solution to Faddeev equations with two-body experimental amplitudes as input and application to J^P=1/2^+, S=0 baryon resonances

We thank Juan Nieves for discussions and for providing us the experimental πN amplitudes. This work is partly supported by DGICYT contract number FIS2006-03438 and the JSPS-CSIC Collaboration agreement No. 2005JP0002, and Grant for Scientific Research of JSPS No. 188661. One of the authors (A.M.T.) is supported by a FPU grant of the Ministerio de Ciencia y Tecnologia. K. P. Khemchandani thanks the support by the Fundacao para a Ciencia e a Tecnologia of the Ministerio da Ciencia, Tecnologia e Ensino Superior of Portugal (SFRH/BPD/40309/2007). This research is part of the EU Integrated Infrastructure Initiative Hadron Physics Project under contract number RII3-CT-2004-506078.

Vector meson-Baryon dynamics and generation of resonances

The purpose of this work is to study vector meson-octet baryon interactions with the aim to find dynamical generation of resonances in such systems. For this, we consider s-, t-, u-channel diagrams along with 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 coupled channel Bethe Salpeter equations for systems with total strangeness zero, show generation of one isospin 3/2, spin 1/2 resonance and three isospin 1/2 resonances: two with spin 3/2 and one with spin 1/2. We identify these resonances with

The N*(1710) as a resonance in the ππN system

\Delta (1900) S_{31}

Relating

,

D^* \bar{D}^*

N^* (2080) D_{13}

currents with

,

J^\pi= 0^+,1^+

N^* (1700) D_{13}

and

, and

2^+

N^*(2090) S_{11}