Form factors in $SU(3)$-invariant integrable models

We study $SU(3)$-invariant integrable models solvable by a nested algebraic Bethe ansatz. We obtain determinant representations for form factors of diagonal entries of the monodromy matrix. This representation can be used for the calculation of form factors and correlation functions of the $XXX$ $SU(3)$-invariant Heisenberg chain.