Nodal trajectories and kaon photoproduction

Using helicity amplitudes, the general structure of the full set of 15 single and double polarization spin observables for the reaction γp → K+Λ has been discussed earlier. Through this model independent approach, general rules on the angular structure of the observables have been derived. The observables in each class have similar 'nodal structure' possibilities, e.g. their values at 0 deg and 180 deg and their possible intervening nodes are of related nature. One of those rules is confronted with three recent dynamical models for the L1a class observables. (K.A.). 5 refs., 1 fig