79 research outputs found
Roper Electroproduction Amplitudes in a Chiral Confinement Model
A description of the Roper using the chiral chromodielectric model is
presented and the transverse and the scalar helicity
amplitudes for the electromagnetic Nucleon--Roper transition are obtained for
small and moderate . The sign of the amplitudes is correct but the model
predictions underestimate the data at the photon point. Our results do not
indicate a change of sign in any amplitudes up to GeV. The
contribution of the scalar meson excitations to the Roper electroproduction is
taken into account but it turns out to be small in comparison with the quark
contribution. However, it is argued that mesonic excitations may play a more
prominent role in higher excited states.Comment: 10 pages, 8 figures, uses World Scientific macros. Talk presented at
EMI2001 in Osaka, Japa
N^* electroproduction amplitudes in a model with dynamical confinement
The Roper resonance is described in a chiral version of the chromodielectric
model as a cluster of three quarks in radial-orbital configuration
(1s)(2s), surrounded by and -meson clouds and by a
chromodielectric field which assures quark dynamical confinement. Radial
profiles for all fields are determined self-consistently for each baryon.
Transverse and scalar helicity amplitudes for the
nucleon-Roper transition are calculated. The contribution of glueball and
-meson vibrations is estimated; although small for N(1440), the
contribution can be large for N(1710).Comment: 12 pages, 6 figures, uses elsevier macro
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