2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/182060Positivity constraints have proved to be important for spin observables of exclusive reactions involving polarized initial and final particles. Attention is focused in this note on the photoproduction of pseudoscalar mesons from spin 1/2 baryons, more specifically gamma+ N -> K+ Lambda, gamma+ N -> K Sigma, for which new experimental data are becoming available.3 pages,RevTex, 1 figure, more details on the derivation, refs. added, to appear in Phys. Rev. CNuclear TheoryHigh Energy Physics - ExperimentHigh Energy Physics - PhenomenologyNuclear Experimenttext