2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/214537We present a method of determining weak phase γin the Cabibbo-Kobayashi-Maskawa matrix from decays B->ηK, η' K$ alone. Given a large ratio between color-suppressed and color-allowed tree diagrams extracted from global ππ(K) fits, γis determined from the current data of η' K and the result is in agreement with the global Standard Model(SM) fits. However, a smaller ratio from factorization based calculations gives $γ\sim 90^\circ$. New physics beyond the SM can be singled out ifγobtained in η^{(')} K modes is significantly different than the ones from other modes or other approaches. The effective value of γfrom η' K is very sensitive to new physics contributions and can be used to extract new physics parameters for a class of models which do not give contributions to strong phases significantly.18 pages, 2 figures, version to appear in Eur.Phys.J.CHigh Energy Physics - Phenomenologytext