Recent content by Gary Weiss

sorry I don't get it... why is it that when tau < 0 I can choose the contour above the real axis and ignore the singularity.

hi I don't understand this bit about the derivation of propagator expressions. Bjorken and Drell describe the step function as: \theta(\tau)=lim_{\epsilon \to 0}\frac{-1}{2\pi i}\oint_{-\infty}^{\infty}\frac{d\omega e^{-i\omega r}}{\omega + i \epsilon } the singularity is at -i \omega...