Lawrence Berkeley National Laboratory

Using the PCAC relation, we derive a compact formula for the pion decay constant Fπ in the nonlocal chiral quark model. For practical calculations this formula may be used both in the Minkowski and in the Euclidean space. For the pion momentum Pμ ← 0 it reduces to the well known expression derived earlier by other authors. Using a generalized dipole Ansatz for the momentum dependence of the constituent quark mass in the Minkowski space, we express Fπ2 in terms of a single integral over the quark momentum fraction μ. We interpret the integrand as a pion distribution amplitude φ(u). We discuss its properties and compare with the πDA's obtained in other models.