Integral of a complex exponential

[mhill]

Homework Statement

let be A_{i,j} a Hermitian Matrix with only real values then

\int_{V} dV e^{iA_{j,k}x^{j}x^{k}}= \delta (DetA) (2\pi)^{n} (1)

Homework Equations

\int_{V} dV e^{iA_{j,k}x^{j}x^{k}} = \delta (DetA) (2\pi)^{n}

The Attempt at a Solution

the idea is that the integral (1) is divergent when the Matrix A is not invertible Det=A and the Dirac delta is not defined at x=0 ,for example if detA=0 then at least one of the eigenvalues is 0 so the exponential takes the value 1 and the integral is divergent

 

[Avodyne]

Try working in the basis in which A is diagonal.