All Questions
6 questions
4votes
2answers
3kviews
QFT generating functional and Green function and propagator
I am confused about why does the generating functional gives the propagator by differentiation, and why that propagator is the Green function. I understand how to take the functional derivative like ...
- 242
3votes
1answer
554views
How to connect Green function to propagator?
I know that there has already been many questions related to this question, such as in Differentiating Propagator, Green's function, Correlation function, etc. However, that question mainly ...
- 503
3votes
1answer
276views
Polchinski book, doubt related to $X_{0}$
I'm reading polchinski's book and I was asking if I've made a wrong calculation or I didn't understand sth. Well, basically. $$Z[p]=\int [DX^{\mu}]e^{-S[X]}e^{ipX}$$ $$=(2\pi)^{d}\delta^{d}(p_{0})\...
- 313
2votes
1answer
644views
Explicit calculation of the two-point function by path integrals
I need help carrying out the following calculation: We have the generating functional of free theory: $$Z[f] = \exp\left(\frac{i}{2} \int d^4xd^4y f(x)f(y)\Delta(x-y)\right) $$ where $f$ is an ...
- 184
1vote
0answers
517views
Green Function generating functional and Fourier transform spaces
I am given the transform of the generating functional for free Klein-Gordon theory, $$Z[J]=N\int D\phi \, e^{i\int d^4 J(x)\phi(x)}\tilde{Z}[\phi]$$ where $\phi(x)$ is a scalar field. I'm a little ...
- 659
1vote
1answer
644views
Does the imaginary time path integral for the partition function imply that temperature set a characteristic time scale for quantum systems?
In the ordinary path integral, the action is an integration over the time your interested in. In quantum statistical mechanics the integration is over an imaginary time with the limit $\frac{\beta}{\...
- 1,454
