Exchange Currents in Photoproduction of Baryon Resonances
نویسنده
چکیده
We calculate photoexcitation amplitudes for all nucleon and ∆ resonances up to √ s=1.6 GeV. We use a chiral quark model including two-body exchange currents. The two-body currents give important contributions. For the ∆(1232) and the D13(1520) we observe that the individual exchange current contributions considerably cancel each other while for the P11(1440), the P33(1600), and the S11(1535) we get a reinforcement of the two-body amplitudes. In comparison with present experimental data, we obtain both for the S11(1535) and for the P11(1440) amplitudes an improvement with respect to the impulse approximation. PACS numbers: 13.60.Rj, 13.40.Gp, 12.39.Pn, 14.20.Gk
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تاریخ انتشار 2008