A genetic algorithm analysis of N∗ resonances in p(γ,K+)Λ reactions Original Research Article

The problem of extracting information on new and known N∗ resonances by fitting isobar models to photonuclear data is addressed. A new fitting strategy, incorporating a genetic algorithm, is outlined. As an example, the method is applied to a typical tree-level analysis of published p(γ,K+)Λ data. It is shown that, within the limitations of this tree-level analysis, a resonance in addition to the known set is required to obtain a reasonable fit. An additional P11 resonance, with a mass of about 1.9 GeV, gives the best agreement with the published data, but additional S11 or D13 resonances cannot be ruled out. Our genetic algorithm method predicts that photon beam asymmetry and double polarization p(γ,K+)Λ measurements should provide the most sensitive information with respect to missing resonances.