Parity violating flavour changing neutral current and natural conservation of strangeness in vector-like theories

Two vector-like schemes of the weak interactions, based on five and seven quarks, respectively, are studied in which the suppression of mod Delta S mod =1 neutral currents is natural and in which the neutral current interaction violates parity. Various aspects (parity violation, flavour changing neutral current, ' nu anomaly', masses of the W and Z bosons) are investigated. (17 refs).