Cohomology theory of Nijenhuis family $\mathrm{\Omega }$-associative algebras

Family algebraic structures indexed by a semigroup first appeared in the algebraic aspects of renormalizations in quantum field theory. In this paper, we first introduce the concept of Nijenhuis family $\mathrm{\Omega }$-associative algebras and we discuss the relationship between Nijenhuis family and other operators families on $\mathrm{\Omega }$-associative algebras. Then, we define the cohomology theory of Nijenhuis family $\mathrm{\Omega }$-associative algebras and show that this cohomology controls the corresponding deformations. Finally, we study abelian extensions of Nijenhuis family $\mathrm{\Omega }$-associative algebras in terms of the second cohomology group.