All Questions
Tagged with cosmology quantum-field-theory
153
questions
-6
votes
0
answers
73
views
How can I visualise a sphere with a negative radius? [closed]
I want to visualise the shape of the sphere , will having a negative radius turn the inside of the sphere outside or something other will happen ?
2
votes
0
answers
44
views
Feynman rule from dynamical Chern-Simons
Consider the following action that
\begin{equation}
S = \int d^4x\sqrt{-g}\left(-\frac{1}{2}(\partial\phi)^2 + V(\phi) + \frac{2R}{\kappa^2}
- \frac{\phi}{4f}{}^*RR\right)
\end{equation}
where
\...
- 704
4
votes
1
answer
186
views
Is gravitational particle production due to symmetry breaking?
A well-known fact about QFTs in curved spacetimes is that there is a phenomenon of particle production in expanding universes, these being described by the line element $$ds^2=-dt^2+b^2(t)d\vec x^2.$$
...
- 495
0
votes
1
answer
47
views
Electrons keeping dynamical quantum fluctuations?
I was thinking about this paper (https://arxiv.org/abs/1405.0298) where the authors argue that there wouldn't be dynamical quantum fluctuations in a De Sitter space as fluctuations would be static ...
- 2,466
0
votes
1
answer
101
views
Trapping Hawking radiation in black holes?
I was reading this writing (https://davidwoolsey.com/AttO/AttO_blog/Entries/2020/7/13_Black_Holes_and_Transverse_Tidal_Effects%2C_a_revised_essay_on_some_thoughts.html) about considering tidal effects ...
- 2,466
0
votes
0
answers
96
views
If dark energy has constant density, would it still be subject to quantum variations; would increase/decrease be symmetrical, or would one take over?
There are different suggestions, but it stills seems like the basic scenario is for dark energy to have constant density, as a property of space (and as represented by the cosmological constant in ...
- 15
2
votes
0
answers
24
views
Why is there an infinite supply of energy in slow-roll inflation?
The physical model of inflation includes a metastable false vacuum, or a slow-roll field on a flat potential. In either case, I just realized how this is completely insane. With the exponential growth ...
- 619
1
vote
3
answers
144
views
Why doesn't frozen-out dark matter annihilate later during structure formation?
The so-called freeze-out of dark matter is based on a homogeneous description. However, in the later stages of the universe, where structures form, it seems very likely that the reaction rate would ...
- 619
2
votes
2
answers
97
views
Why does the mechanism producing matter-antimatter asymmetry keep our universe electrically neutral? Any general argument?
I've noticed what seems to be a fine-tuning issue. To be more specific, electric neutrality implies that the amount of lepton asymmetry produced through some unknown processes precisely cancels out ...
- 619
0
votes
0
answers
52
views
False Vacuum State (QFT)
I am wondering if someone can refer me to a proof that the false vacuum state is a natural consequence of scalar field theories? I see that being said in a lot of texts on cosmology when discussing ...
- 1
0
votes
0
answers
98
views
Three-Point correlation function in cosmology
I have been studying this review article on Non-Gaussianity from inflation. It was mentioned that $n$-point correlation function can be obtained by the expression
\begin{equation}\label{eq:1}
\langle\...
1
vote
0
answers
72
views
Exact solution to the Mukhanov-Sasaki equation for a massless scalar field
I am reading some cosmology review papers and I am at the section in which the equation of motion for a massless scalar field in a de Sitter spacetime is derived. The equation of motion for the ...
- 11
1
vote
1
answer
88
views
Cosmological Constant Problem calculations involving energy densities
I am following Timo Weigand lecutre notes on QFT, on page 28, he breifly touches on the Cosmological Constant Problem.
But I am a little confused.
He begins with a Lagrangian and include a nonzero $V_{...
- 487
4
votes
1
answer
99
views
What do the authors of the paper mean here exactly by path integral?
First of all, please forgive me if i am asking a dumb question. I don't have a physics background. I was reading this paper by Hawking & Hertog on populating string theory landscape and came ...
- 67
1
vote
2
answers
151
views
Whether vacuum energy gravitate?
What is the relationship between vacuum energy and gravity, particularly in terms of gravitational effects and its contribution to the overall cosmological constant? Does vacuum energy possess ...
