2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/37239A decade long search for the rare kaon decay to pi^+nunu-bar has been pursued by E787. Two signal events are observed, giving a measurement of the branching ratio Br(K^+ -> PI^+NUNU-BAR)=1.57^+1.75_-0.82 x 10^-10 and a constraint on the Cabibbo-Kobayashi-Maskawa (CKM) matrix element 0.007<|Vtd|<0.030 (68% C.L.).Contributed to the XXXVIIth Rencontres de Moriond session for Electroweak Interactions And Unified TheoriesHigh Energy Physics - Experimenttext