How to solve the following differential equation with tensor indices?
$\epsilon_{\mu\nu}\partial^{\gamma}\partial_{\gamma}f-2i\epsilon_{\mu\nu}p.\partial f+ip_{\mu}x^{\gamma}\epsilon_{\nu\gamma}+ip_{\nu}x^{\gamma}\epsilon_{\mu\gamma}-i(p.x)\epsilon_{\mu\nu}+2\epsilon_{\mu\nu}=0$
Here $\epsilon_{\mu\nu}$ is the usual polarization tensor for gravity and only depends on the momentum $p$. The derivatives are with respect to $x$.
