All Questions
Tagged with quantum-field-theory wick-rotation
156
questions
2
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303
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How are Schwinger and Wightman functions used in practice?
In Reed & Simon's Methods of Mathematical Physics Volume II, they define a (Hermitian scalar) quantum field theory to be the quadruple $\langle \mathcal{H}, U, \varphi, D\rangle$ that satisfies ...
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Path Integral for Unruh Effect
In derivation of Unruh effect, according to arxiv 2108.09188, we have
$$
\langle\phi_L|\exp(-\pi H)|\phi_R\rangle=\int_{\phi=\phi_R}^{\phi=\phi_L} D\phi e^{-S_E}\propto \int_{lower\space half\space ...
- 133
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Why we can Wick rotate momentum axis for correlation function?
In QFT writtern by Peskin and Schroeder, in page 293, PS wick rotate both time axis and momentum axis of correlation function of Klein-Gordon field, ie
$$D_F=<0|T\phi(x_1)\phi(x_2)|0>=\int\frac{...
- 326
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1
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Do we wick rotate momentum axis on correlation function?
In QFT written by Peskin and Schroeder, it is discussed how correlation function is evaluated in Euclidean space, on page 292 to 293,
In (9.48)
$$<\phi (x_{E1})\phi(x_{E2})>=\int \frac{d^4k_E}{(...
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1
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295
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Why do we Wick rotate before regularizing Feynman diagrams?
In Folland's Quantum Field Theory he mentions that we can apply Feynman's formula (Feynman parameterization) to either the Wick rotated integrals or the non-Wick rotated integrals corresponding to ...
- 3,350
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123
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Correlators on the Euclidean section of a black hole
In the standard construction of the Euclidean section of a Schwarzschild black hole, we start with the exterior metric in Schwarzschild coordinates:
$$\tag{1} ds^2 = -(1-r_s/r)dt^2 + (1-r_s/r)^{-1}dr^...
- 1,455
1
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1
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Performing Wick rotation under conjugation
See the formulas (95) and (96) of this notes https://arxiv.org/abs/1602.07982. When one try to perform the Wick rotation $t=-i\tau$ to the field in Minkowski/Lorentzian spacetime
$$\mathcal{O}_L(t, \...
- 161
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3
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Wick rotation in Peskin and Schroeder's QFT
I know there are many similar analysis about this topic, like here, here, many of them are answered by Qmechanic, excellent answer!
I have checked most of these posts, but I still don't clearly ...
- 1,421
3
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153
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Green Function in Euclidean space time
My question based on Ashok Das's "Finite Temperature Field Theory", page 12-13.
The book assume that in bosonic Klein-Gordon theory, zero temperature Green function satisfies (metric in ...
- 1,421
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0
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Can the QFT path integral be re-expressed using a real, positive-definite function of the action? [duplicate]
This question is based on my rather shaky grasp of QFT, so if I'm missing a key concept then just let me know!
If you're deriving the Schrodinger equation from the path integral as Feynman did, then ...
- 2,475
3
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1
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331
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Continuum limit of lattice field theory
Just a simple question for lattice QCD experts, is continuum limit of lattice field theory a relativistic quantum field theory?
Because i heard that lattice QCD is done in imaginary time, producing a ...
- 343
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Physics in Euclidean spacetime [duplicate]
I just have a very small and naive Question.
In my PhD I work on different Toy models which are implemented on the lattice.
In order to do so one performs a Wick rotation from minkowski to euclidean ...
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1
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365
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Chiral symmetry of the Euclidean action for fermions
In the literature, such as QFT Volume-II by Weinberg, p.368, the chiral anomaly is derived using Euclidean path integral. To formulate the question, let's start with the Minkowski space with signature ...
8
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4
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680
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Is the value of the action important?
I know that the action, in Classical Mechanics, is a functional of the path of a physical system, such that
"the path actually followed by a physical system is that for which the action is ...
- 5,931
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108
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Why is the Vacuum state got by a limit to imaginary time?
Given a (non-relativistic) propagator $K_t(A,B)$ giving the 'conditional amplitude' to go from state $B$ to state $A$ in time $t$, it is known that one can find the vacuum wavfunction by (independent ...
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