# Gaussian Integral with Denominator in QFT

1. Apr 2, 2015

### "pi"mp

Hi all, so I've come across the following Gaussian integral in QFT...but it has a denominator and I am completely stuck!

$$\int_{0}^{\infty} \frac{dx}{(x+i \epsilon)^{a}}e^{-B(x-A)^{2}}$$

where a is a power I need to leave arbitrary for now, but hope to take between 0 and 1, and $\epsilon$ is arbitrarily small.

Does any one have any suggestions on how to tackle this? If not, I'd like to leave a arbitrary, but perhaps is can be set to 1/2. Would this then be doable? Thanks for any help!!

2. Apr 3, 2015

### RUber

$\int_0^\infty \frac{e^{-B(x-A)^2}}{(x+i\epsilon)^a} \, dx$ could be rewritten as $\int_{i \epsilon} ^\infty \frac{e^{-B(z-A-i\epsilon)^2}}{(z)^a} \, dz$
I am thinking some sort of complex integration technique might help.