This is more of a math question than a physics one, but following the discussion of the propagator in Zee's book:(adsbygoogle = window.adsbygoogle || []).push({});

-(∂^{2}+m^{2})D(x-y)=δ(x-y)

he then gets, by taking the Fourier transform of the Dirac delta and dividing through:

D(x-y) = [itex]\int\frac{d^4k}{2π^4} \frac{e^{ik(x-y)}}{k^2-m^2+iε}[/itex]

I get the FT and adding iε to avoid a pole, but not how you take

D(x-y)= -(∂^{2}+m^{2})^{-1}[itex]\int\frac{d^4k}{2π^4} e^{ik(x-y)}[/itex]

and change the differential operator outside the integral to [itex]1/ (k^2-m^2) [/itex] inside it

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Help deriving propagator

**Physics Forums | Science Articles, Homework Help, Discussion**