Abstract
The purpose of this paper is to construct the calculus of variations for general zero mean processes with independent increments and, in particular for Lévy processes. The calculus based on the operators D and $\delta$, is such that for the Gaussian processes they coincide with the Malliavin derivative and Skorohod integral, respectively. We introduce the family of polynomials which contains the Sheffer set of polynomials. By using these polynomials it is proved that the operators D and $\delta$ are equal respectively to the annihilation and the creation operators on the Fock space representation of $L^2(\Omega)$.