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Helicity Amplitudes In the Hypercentral Constituent Quark Model

M. M. Giannini·E. Santopinto·A. Vassallo
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Abstract

We report on the recent results of the hypercentral constituent quark model. The model contains a spin independent three-quark interaction which is inspired by QCD lattice calculations and reproduces the average energy values of the SU(6) multiplets. The splittings are obtained with a residual generalized SU(6)-breaking interaction, including an isospin dependent term. The long standing problem of the Roper resonance is absent and all the 3- and 4-star states are well reproduced. The model has also been used for predictions concerning the electromagnetic transition form factors giving a good description of the medium $Q^2$ -behaviour. In particular the calculated $S_{11} A_{1/2}$ helicity amplitude agrees very well with the recent CLAS data. Finally the ratio of the elastic form factors of the proton, calculated including kinematic relativistic corrections, exhibits a substantial decreasing with $Q^2$ in agreement with the recent TJNAF experiment.

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M. M. Giannini, E. Santopinto, A. Vassallo. 2003-01-07. Helicity Amplitudes In the Hypercentral Constituent Quark Model. https://doi.org/10.1142/9789812705167_0038

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