Suppose you have the following ward identity: ∫Md4x ϵ(x) ∂μ⟨jμ(x)O(y)⟩=− ⟨δO(y)⟩
where
δO(y) can be written in the following way to get the usual local form of the ward identity:
δO(y)=∫Md4x δ(x−y) ϵ(x) δO(y)
Now suppose we choose ϵ (which is arbitrary) such that it's costant in M. Is it possible to use Stokes theorem and get : ∫∂Mdσμ ⟨jμ(x)O(y)⟩=− ⟨δO(y)⟩
or are we neglecting contact terms given by the
T product by doing so? Moreover is it possible to do the spectral decomposition of
⟨jμ(x)O(y)⟩ even if it's integrated?