All Questions
Tagged with quantum-field-theory particle-physics
1,059
questions
182
votes
5
answers
25k
views
Gauge symmetry is not a symmetry?
I have read before in one of Seiberg's articles something like, that gauge symmetry is not a symmetry but a redundancy in our description, by introducing fake degrees of freedom to facilitate ...
- 17.1k
95
votes
6
answers
18k
views
What is more fundamental, fields or particles?
My confusion about quantum theory is twofold:
I lack an adequate understanding of how the mathematics of quantum theory is supposed to correspond to phenomena in the physical world
I still have an ...
- 1,141
73
votes
7
answers
17k
views
Why isn't Higgs coupling considered a fifth fundamental force?
When I first learned about the four fundamental forces of nature, I assumed that they were just the only four kind of interactions there were. But after learning a little field theory, there are many ...
- 1,070
58
votes
1
answer
7k
views
Why are particles thought of as irreducible representations, in plain English?
I'm a PhD student in mathematics and I have no problem in understanding what irreducible representation are. I mean that the mathematical side is not a particular problem. Nevertheless I have some ...
- 944
48
votes
2
answers
17k
views
Weak force: attractive or repulsive?
We are always told that there are the four fundamental forces or interactions of nature: gravitation, electromagnetism, and the weak and strong forces. We know that gravitation is attractive, that ...
- 975
46
votes
1
answer
2k
views
Resolving Conflicting Reports on Fermilab $g-2$ Results
Today it was announced that the Fermilab measurements of the muon's gyromagnetic ratio are in disagreement with the Standard Model with a statistical certainty reported at 4.2 sigma [1, 2], raising ...
- 3,710
43
votes
5
answers
24k
views
What's the difference between helicity and chirality?
When a particle spins in the same direction as its momentum, it has right helicity, and left helicity otherwise. Neutrinos, however, have some kind of inherent helicity called chirality. But they can ...
- 433
39
votes
2
answers
13k
views
How does the Higgs mechanism work?
I'm not a particle physicist, but I did manage to get through the Feynman lectures without getting too lost.
Is there a way to explain how the Higgs field works, in a way that people like me might ...
- 17.1k
36
votes
5
answers
6k
views
Why do we observe particles, not quantum fields?
My understanding is that, in the context of quantum field theory, particles arise as a computational tool. We perform an expansion in the path integral in some parameter, and the terms in these ...
- 1,590
34
votes
3
answers
11k
views
Would a spin-2 particle necessarily have to be a graviton?
I'm reading often that a possible reason to explain why the Nobel committee is copping out from making the physics Nobel related to the Higgs could be, among other things, the fact that the spin of ...
- 9,581
34
votes
4
answers
4k
views
"Slightly off-shell"?
I'm not new to QFT, yet there are some matters which are quite puzzling to me. I often come across the statement that real particles (the ones we actually measure in experiments, not virtual ones) are ...
- 15.8k
33
votes
2
answers
11k
views
The concept of particle in QFT
I never learnt QFT and I apologize for my (probably) elementary question. Somebody told me that in QFT a particle is viewed as an irregularity in the field.
On the other hand, in an article in ...
- 6,896
33
votes
3
answers
5k
views
What is the physical interpretation of second quantization?
One way that second quantization is motivated in an introductory text (QFT, Schwartz) is:
The general solution to a Lorentz-invariant field equation is an integral over plane waves (Fourier ...
- 753
33
votes
3
answers
3k
views
What exactly is a pomeron?
The term 'pomeron' was apparently important in the early stages of QCD. I can't find any reference to it in modern QFT books, but older resources sometimes refer to it offhand, and I've yet to find ...
- 103k
31
votes
2
answers
6k
views
How are bound states handled in QFT?
QFT seems very well suited to handle scattering amplitudes between particles represented by the fields in the Lagrangian. But what if you want to know something about a bound state without including ...
- 28.3k