Eur. Phys. J. A 11, 217-230 (2001)
Quark model study of the 
photo-production:
Evidence for a new S11 resonance?
B. Saghai1 and Z. Li21 Service de Physique Nucléaire, DAPNIA - CEA/Saclay, F-91191 Gif-sur-Yvette Cedex, France
2 Physics Department, Peking University, Beijing 100871, P.R. China
bsaghai@cea.fr
(Received: 14 February 2001 / Revised version: 22 June 2001 Communicated by V. Vento)
Abstract
An extensive and systematic study of the recent photo-production
data up to 1.2 GeV is presented within a chiral constituent quark model.
A model embodying all known nucleonic resonances
shows clear need for a yet undiscovered third S11 resonance in the
second resonance region, for which we determine the mass (1.729 GeV) and
the total width (183 MeV).
Furthermore, we extract the configuration mixing angles, an
important property of the quark-quark interaction in the quark model,
for the resonances
S11(1535) and
S11(1650), as well as for
the resonances
D13(1520) and
D13(1700). Our results agree well with the
quark model predictions.
In addition, the partial 
decay widths and/or the photo-excitation
helicity amplitudes for the nucleonic resonances
S11(1535),
S11(1650),
P11(1710),
P13(1720),
D13(1520),
D13(1700),
D15(1675), and
F15(1680) are also obtained in this approach.
12.39.Fe - Chiral Lagrangians.
13.40.Hq - Electromagnetic decays.
13.60.Le - Meson production.
14.20.Gk - Baryon resonances with S=0 .
© Società Italiana di Fisica, Springer-Verlag 2001
