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. Li<sup>2

1</sup>  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.

PACS
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