All Questions
Tagged with quantum-field-theory particle-physics
262
questions with no upvoted or accepted answers
11
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0
answers
2k
views
On the naturalness problem
I know that there are several questions about the naturalness (or hierarchy or fine-tunning) problem of scalars masses in physics.stackexcange.com, but I have not found answers to any of the following ...
- 6,889
9
votes
0
answers
516
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Integration & bremsstrahlung calculation
In this paper (relevant pdf section) that I'm reading, involving the calculation of bremsstrahlung in electron proton scattering (diagram below), the author calculates the integral over outgoing ...
- 692
8
votes
0
answers
140
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Axial and vector resonances in composite Higgs models
Is there a reason to believe that the axial resonances are heavier than the vector resonances in the composite Higgs models?
For instance, in this article, to have zero tree level contributions to S ...
- 136
6
votes
1
answer
273
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Photon-Gluon annihilation in QCD
I am starting to learn about QCD, and I wanted to calculate the squared matrix elements for photon-gluon annihilation into a quark and an anti-quark. However, I am having trouble writing down the ...
- 305
6
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0
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235
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Which explanation of the OZI rule is correct (or most important)?
The OZI rule states that a QCD diagram is suppressed if it can be cut into two by only cutting gluon lines (the precise wording is addressed in the question What is the precise statement of the OZI ...
- 585
6
votes
0
answers
809
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Why isn't energy conserved in time-ordered diagrams?
I'm new to particle physics, and I'm reading chapter 5 of Prof. Mark A. Thompson's "Modern Particle Physics", which talks about Time-ordered perturbation theory vs QED. However, in page 119 he wrote:
...
- 700
6
votes
0
answers
227
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Categorizing solutions to Hierarchy problem
We know that no gauge symmetry can prevent a term $m_\phi^2|\phi|^2$ for a scalar field, and that, given the quadratic loop corrections, the natural scale is $m_\phi \sim M_P$. This is related to the ...
- 15.2k
6
votes
0
answers
154
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Seeking chiral anomaly EFT example
If an effective field theory has a chiral anomaly it means that chiral symmetry isn't a symmetry of the underlying theory which has been cut off to make the EFT. My question is whether there's a good ...
5
votes
0
answers
230
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Another "real vs virtual particle" one: calculate the full diagram or $\sigma \times \mathrm{BR}$?
I have recently been forced to think about something I always thought that I understood but that, in reality, I could not be more confused about.
Suppose I want to study the LHC prospects for ...
- 1,742
5
votes
0
answers
294
views
Every possible QFT from positive geometry?
Physicist Nima Arkani-Hamed has taken an interesting approach to understand fundamental physics based on geometry (specifically, positive geometry constructions). This started with his work with ...
- 2,462
5
votes
0
answers
181
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How do you understand displaced vertices rigorously in quantum field theory?
When you produce a long-lived particle (like charged pions, muons), it enters your detector. When you produce a short-lived particle (like the higgs, tau), the production of the particle is only seen ...
- 7,434
5
votes
0
answers
94
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Figure of $SO(10)$ grand unified theory in $E_6$ from Wikipedia
In this figure from Wikipedia, it shows that the representations of particles of $SO(10)$ grand unified theory, their patterns of charges for particles in the $SO(10)$ model, rotated to show the ...
- 4,336
5
votes
0
answers
2k
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Advanced quantum field theory by David Tong
In his freely available lectures on Gauge Theories and String Theory, David Tong makes multiple references to a course called Advanced Quantum Field Theory (in particular, the Faddeev-Popov trick ...
5
votes
0
answers
424
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Is there precision experimental evidence for Furry's theorem -- that only even degree VEVs are non-zero?
Is there precision experimental evidence for or contradicting Furry's theorem -- that only even degree VEVs are non-zero, specifically for the EM field?
- 9,948
4
votes
1
answer
72
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How does path integral quantization ensure unitarity?
Unitarity can be verified post hoc by examining the optical theorem. In the context of path integral quantization where formal derivation starting from canonical quantization is unavailable, is it ...
- 619