- #1

taishizhiqiu

- 63

- 4

1. Is green's function well defined at this point?

2. if green's function is well defined at this point, is it continuous here?

3. In quantum many body theory, I am instructed to view ##G_0(x,t;x,t)## as ##G_0(x,t;x,t+0^+)## in feynman diagrams. Why is this so?