All Questions
9
questions
0
votes
1
answer
56
views
Non-minimally coupled inflation
In Wikipedia you can read under the Keyword Inflaton , the Formula:
What do the individual formula symbols mean in the following formula:
$$S=\int d^{4}x \sqrt{-g} \left[\frac{1}{2}m^2_{P}R-\frac{1}{2}...
- 11
5
votes
3
answers
717
views
Are there fields (of any kind) inside a black hole?
It is said that nothing escapes from black holes, not even light. All particles are now thought to be excitation of different fields (electric field, electromagnetic field, photon field, etc).
Does it ...
- 137
3
votes
1
answer
264
views
Energy-momentum tensor in two-dimensional spacetime
If we consider the following 2D theory
$$S=\int d^2 x\sqrt{-g}\left(R+\mathcal{L}_{\rm matter}\right).$$
I understand that the gravity is trivial in two-dimensional spacetime because the Einstein ...
- 3,691
1
vote
0
answers
261
views
Canonical Quantization in QFT in curved spacetime
Let $\varphi(x)$ be a scalar field propagating on some curved background $g_{\mu\nu}$, satisfying the field equation
\begin{equation}
D[\varphi] = 0
\end{equation}
where $D$ is some differential ...
- 31
7
votes
1
answer
3k
views
Why do we impose de Donder gauge?
In the field language, a massless particle corresponds to irreducible representations of the Lorentz group. In particular, given a spin-2 massless particle, we can embed the creation and annihilation ...
- 2,197
4
votes
1
answer
354
views
S-duality of Einstein-Maxwell-Dilaton theory
Consider theory with action
$$S = \int d^D x \sqrt{-g} (R - \frac{1}{2} \partial_\mu \phi \partial^\mu \phi - \frac{1}{2k!} e^{a \phi} F^2 _{[k]} ) $$
where $\phi$ is dilaton and $F_{[k]}$ is ...
- 546
1
vote
1
answer
285
views
Equivalence principle for test fields
My question is very simple. We all know that, for a test particle(classical) in a gravitational field, the motion is only determined by the geodesic lines(let's forget about the initial conditions for ...
- 65
35
votes
2
answers
10k
views
Energy-Momentum Tensor in QFT vs. GR
What is the correspondence between the conserved canonical energy-momentum tensor, which is $$ T^{\mu\nu}_{can} := \sum_{i=1}^N\frac{\delta\mathcal{L}_{Matter}}{\delta(\partial_\mu f_i)}\partial^\nu ...
- 2,024
4
votes
1
answer
509
views
Definition of vacuum in field theory; Connection between the classical definition and the connection to QFT
I am a bit confused by what is defined to be a vacuum in field theory.
Classically a vaccum state is defined to be the state where the field sits at some minima of the potential $\frac{\partial V}{\...
- 171