A study of the Roper resonance as a hybrid state from image decays Original Research Article

The structure of the Roper resonance as a hybrid baryon is investigated through studying the transitional amplitudes in View the MathML source, View the MathML source decays. We begin with perturbative QCD to describe the dynamical process for the View the MathML source decay to the lowest order of αs, and by extending the modified quark creation model to the J/ψ energy region to describe the View the MathML source process. The nonperturbative effects are incorporated by a simple quark model of baryons to evaluate the angular distribution parameters and decay widths for the processes View the MathML source, View the MathML source. From fitting the decay width of View the MathML source to the experimental data, we extract the quark-pair creation strength gI=15.40 GeV. Our numerical results for View the MathML source, View the MathML source decays show that the branching ratios for these decays are quite different if the Roper resonance is assumed to be a common 3q state or a pure hybrid state. For testing its mixing properties, we present a scheme to construct the Roper wave function by mixing |qqqg〉 state with a normal |qqq,2s〉 state. Under this picture, the ratios of the decay widths to that of the View the MathML source decay are re-evaluated versus the mixing parameter. A test of the hybrid nature of the Roper resonance in J/ψ decays is discussed.