Olga Aryasova (Inst. of Geophysics, Nat. Acad. of Sciences of Ukraine / Friedrich–Schiller–Univ. Jena)
Claudio Dappiaggi (Pavia)
We apply the algebraic approach to construct the algebra of observables associated to non linear Sigma models. In particular we discuss the notion of Wick polynomials and their realization in terms of the so-called Hadamard regularization.