Speaker
Mr
Simon Sirca
(Faculty of Mathematics and Physics, University of Ljubljana)
Description
We present a method to calculate pion scattering and
electro-production amplitudes in a coupled-channel framework
incorporating quasi-bound quark-model states. All relevant
low-lying nucleon resonances in the P33, P11, and S11 partial waves
have been covered, including the Delta(1232), the N*(1440) and,
most recently, the negative-parity resonances N*(1535) and
N*(1650). The strong and electro-magnetic vertices of resonances
are computed in the chosen quark model and not fitted. We show that
even in a model as simple as the Cloudy Bag, a consistent
description of the amplitudes can be achieved by using the same
parameter set for all resonances. The meson cloud has been shown
to play a major role, in particular in electro-magnetic observables
for resonances in the P33 and P11 channels. However, the meson cloud
is not strong enough to support quasi-bound states of baryons and
mesons, as is the case in some models of N*(1440) and N*(1535).
Consistent results were also obtained for the inelastic processes
(two-pion, eta-N, and K-Lambda channels).
Primary author
Mr
Simon Sirca
(Faculty of Mathematics and Physics, University of Ljubljana)
Co-author
Bojan Golli
(Faculty of Education, University of Ljubljana)
