I am trying to calculate the first order photon self-energy.

At a point, I must calculte the following integral :

[tex] \int d^4k \frac{(k+q)^\mu k^\nu+(k+q)^\nu k^\mu - g^{\mu \nu}(k \cdot(k+q) - m^2}{k^2 + 2x(q\cdot k) + xq^2 -m^2} [/tex]

I know that I must wick rotate and that [tex] k^2[/tex] will become [tex]-k_E^2[/tex].

But I don't know what terms like [tex] (k+q)^\mu k^\nu[/tex] will become.

Can anybody help me?

Thank you