Calculations of the Decay Constant and Radius of the Pion

We calculated the decay constant and radius of the pion in the framework of the Bethe-Salpeter equation with the vector-vector-type flat-bottom potential.The calculated results,f_(π)=102MeV and<r_(π)^(2)>^(1/2)=0.632fm,are close to experimental values of f_(π)=93 MeV and<r_(π)^(2)>^(1/2)=0.663±0.023fm.