title: Instantons and the DeltaI = 1/2 rule.
abstract: The instanton-induced interaction leads to a significant enhancement of the Ao weak amplitude determining the DeltaI = 1/2 rule, through the contribution of operators with dimension d = 9, as we show in the weak K--> pi(pi) decay.
authors.affiliation: Departament de Física Teòrica and Institut de Física Corpuscular, Universitat de València-CSIC, Spain.
authors.forename: N I
authors.initials: NI
authors.lastname: Kochelev
authors.forename: V
authors.initials: V
authors.lastname: Vento