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The European Physical Journal A

, Volume 39, Issue 2, pp 195–204 | Cite as

The role of the qqqq\( \bar{{q}}\) components in the electromagnetic transition \( \gamma^{{*}}_{}\)N → N*(1535)

  • C. S. An
  • B. S. Zou
Regular Article - Theoretical Physics

Abstract

The helicity amplitudes A p 1/2 and S p 1/2 for the electromagnetic transition \( \gamma^{{*}}_{}\) NN *(1535) are calculated in the quark model that is extended to include the lowest-lying qqqq \( \bar{{q}}\) components in addition to the qqq component. It is found that with admixture of 5-quark components with a proportion of 20% in the nucleon and 25-65% in the N *(1535) -resonance the calculated helicity amplitude A p 1/2 decreases at the photon point, Q 2 = 0 to the empirical range. The qqqq \( \bar{{q}}\) components contain s \( \bar{{s}}\) pairs, which is consistent with the substantial width for N \( \eta\) decay of the N *(1535) . The best description of the momentum dependence of the empirical helicity amplitudes is obtained by assuming that the qqqq \( \bar{{q}}\) components are more compact than the qqq component. However, this version of the extended quark model still does not lead to a satisfactory simultaneous description of both A p 1/2 and S p 1/2 although with significant improvement.

PACS

12.39.Jh Nonrelativistic quark model 14.20.Gk Baryon resonances with S = 0 

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Copyright information

© SIF, Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • C. S. An
    • 1
    • 2
  • B. S. Zou
    • 1
    • 3
  1. 1.Institute of High Energy PhysicsCASBeijingChina
  2. 2.Helsinki Institute of PhysicsUniversity of HelsinkiHelsinkiFinland
  3. 3.Theoretical Physics Center for Science FacilitiesCASBeijingChina

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