Radiative Decay Constant of Pion

This is my first work that I did for the fulfillment of the requirements for MSc. degree. In this work our purpose is to calculate the pion radiative decay constant using the formulation of Bethe-Salpeter equation under covariant Instantaneous Ansatz(CIA)after inclusion of both leading(LO) as well as next-to-leading(NLO) terms in the BS wave function of the pion. In this process we also calculate the pion Bethe-Salpeter Normalizer which is an extremely lengthy calculation.