New graphical criterion for the selection of complete sets of polarization observables and its application to single-meson photoproduction as well as electroproduction

This paper combines the graph-theoretical ideas behind Moravcsik's theorem with a completely analytic derivation of discrete phase-ambiguities, recently published by Nakayama. The result is new graphical procedure for certain types complete sets observables an amplitude-extraction problem $N$ helicity-amplitudes. applied to pseudoscalar meson photoproduction ($N = 4$ amplitudes) and electroproduction 6$ amplitudes), yielding minimal length $2N$ observables. For case electroproduction, this first time extensive list published. Furthermore, generalization proposed processes larger number amplitudes, i.e. $N > sketched. generalized outlined next more complicated example two-meson 8$ amplitudes).