A genetic algorithm analysis of N* resonances in p(gamma, K+)Lambda reactions

摘要

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(gamma, K+)Lambda 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 P-11 resonance, with a mass of about 1.9 GeV, gives the best agreement with the published data, but additional S-11 or D-13 resonances cannot be ruled out. Our genetic algorithm method predicts that photon beam asymmetry and double polarization p(gamma, K+)Lambda measurements should provide the most sensitive information with respect to missing resonances. (C) 2004 Elsevier B.V. All rights reserved.