- #1
Phymath
- 184
- 0
Homework Statement
from Zee QFT in a nutshell
the free propagator between two "sources" on the field is given by[tex] D(x_\mu) = -i \int \frac{d^3k}{(2\pi)^3 2 \omega_k}[e^{-i(\omega_kt-k\bullet x)} \Theta(x_0) + e^{i(\omega_k t-k\bullet x)} \Theta(-x_0) [/tex]
for a space like separation ([tex] x_0 = 0 [/tex]) Zee gets
[tex]
-i\int\frac{d^3k}{(2\pi)^3 2 \omega_k}e^{-i k\bullet x}
[/tex]
with assumption that [tex] \Theta(0) = 1/2 [/tex]
with that assumption i don't agree with Zee i get
[tex]
-i\int\frac{d^3k}{(2\pi)^3 2 \omega_k}cos(k \bullet x)
[/tex]
where am I going wrong?