Kazem Haghnejad Azar - University of Mohghegh Ardabili
Mostfa Shams - Islamic Azad University

Let B be a Banach A-bimodule. We introduce the weak topological centers of left module action and we show it by \tilde{{Z}}^\ell_{B^{**}}(A^{**}). For a compact group, we show that L^۱(G)=\tilde{Z}_{M(G)^{**}}^\ell(L^۱(G)^{**}) and on the other hand we have \tilde{Z}_۱^\ell{(c_۰^{**})}\neq c_۰^{**}. Thus the weak topological centers are different with topological centers of left or right module actions.In this manuscript, we investigate the relationships between two concepts with some conclusions in Banach algebras. We also have some application of this new concept and topological centers of module actions in the cohomological properties of Banach algebras, spacial, in the weak amenability and n-weak amenability of Banach algebras.

Weak topological center, Amenability, Weak amenability, Cohomology groups