All Questions
Tagged with cosmology quantum-field-theory
151
questions
32
votes
4
answers
13k
views
Why is quantum gravity non-renormalizable?
The book The Ideas Of Particle Physics contains a brief treatment of quantum gravity, in which the claim is asserted that if one attempts to construct a model of gravity along the same lines as QED, ...
- 95.5k
20
votes
3
answers
8k
views
Why do neutrino oscillations imply nonzero neutrino masses?
Neutrinos can pass from one family to another (that is, change in flavor) in a process known as neutrino oscillation. The oscillation between the different families occurs randomly, and the likelihood ...
- 1,516
15
votes
3
answers
2k
views
What are quantum fluctuations, really?
So, I have read a lot about quantum fluctuations, and how they are responsible for:
Lamb shift
Spontaneous emission of photons from excited atomic states
Casimir effect
...
and the explanation ...
- 24.9k
12
votes
2
answers
2k
views
The difference between The Dilaton and The Radion?
I have read this question on the Dilaton, but I am a little confused with the distinction between the Dilaton and the Radion.
I definitely have the feeling that these two scalar fields are different ...
- 1,617
9
votes
1
answer
2k
views
Dirac Equation in General Relativity
Dirac equation for the massless fermions in curved spase time is $γ^ae^μ_aD_μΨ=0$, where $e^μ_a$ are the tetrads. I have to show that Dirac spinors obey the following equation:
$$(−D_μD^μ+\frac{1}{4}R)...
- 353
9
votes
1
answer
601
views
What is meant by the term "value" of a scalar quantum field?
During the slow roll of a scalar field, the scalar field is changing its value over time. But what is meant by the term "value" of a scalar field? Since the scalar field is quantized, I don't ...
- 217
8
votes
3
answers
1k
views
Physical origin of the inflaton field?
I have two particular questions regarding the inflationary scenario. They are:
What is the physical origin of the inflaton field?
Why has the potential of the inflation field its particular form?
- 1,323
8
votes
1
answer
307
views
What is the concept of cosmic strings?
What is the concept of cosmic strings? Is it related to the strings in the string theory, and if it is, then how?
- 181
8
votes
0
answers
258
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The emergence of space-time from entangled states
I recently read an article by Yasunori Nomura (https://arxiv.org/abs/1711.05263), in which he says that space-time is an emerging phenomenon. At the same time, space-time disappears when the ...
- 956
8
votes
0
answers
145
views
Does the Standard Model plasma develop a spontaneous magnetisation at finite temperature?
Reference: arXiv:1204.3604v1 [hep-ph] Long-range magnetic fields in the ground state of the Standard Model plasma.
Alexey Boyarsky, Oleg Ruchayskiy, Mikhail Shaposhnikov.
The authors of this paper ...
- 16.6k
7
votes
5
answers
8k
views
Nothing vs. empty space
This question quotes Hawking saying:
[...] you enter a world where conjuring something out of nothing is possible (at least, for a short while). That's because at this scale particles, such as ...
- 676
7
votes
1
answer
3k
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What is a slow-roll field?
I am studying inflation reading this article http://lanl.arxiv.org/abs/hep-ph/0406191 and in section 3 it states:
This inflaton field may evolve slowly down its effective potential, or not. While ...
- 328
7
votes
1
answer
511
views
Does zero point energy really contribute to the cosmological constant?
The zero point energy is usually supposed to contribute to the cosmological constant. And the mismatch between the small cosmological constant compared with the huge zero point energy is deemed as one ...
- 4,452
7
votes
0
answers
132
views
Is GR the only theory in physics which cares about absolute energy?
In my QFT course, they justify dropping the vacuum energy as 'physics only cares about relative energies except for GR in the stress-energy tensor'.
Is this strictly true?
- 2,604
7
votes
0
answers
438
views
750 GeV diphoton resonance: KK graviton?
As everybody of you may know at LHC they found this probable resonance (https://cds.cern.ch/record/2114808, https://cds.cern.ch/record/2114853?ln=en). It may be a scalar or a KK graviton mode. Now, ...
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