7.2. Perturbative series Consider the one-dimensional integral I() = + dxex2+x4 . Write the perturbative

7.2. Perturbative series Consider the one-dimensional integral I(λ) = 

+∞

−∞

dxe−αx2+λx4 .

Write the perturbative series of this expression expanding the term e−λx4 in power series of λ. Compute the perturbative coefficients and show that the series has zero radius of convergence. Give a simple argument of this fact.