All Questions
Tagged with quantum-fields or quantum-field-theory
14,510 questions
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Solving a field in terms of another
Say you have a quantum field theory involving two interacting fields $f_1$, $f_2$, with hamiltonian
\begin{equation}
H = H_{free} + H_{int},
\end{equation}
where $H_{free}$ describes the evolution of ...
- 401
5
votes
1
answer
138
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What is the connection between renormalizability and renormalization group classifications?
A quantum field theory can be classified as superrenormalizable, renormalizable, or nonrenormalizable and in the renormalization group an operator can be classified as relevant, marginal, or ...
- 4,908
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Quantum Entanglement Field Theory by Ammar Hafeez [closed]
Is it possible for entanglement to be a dynamic field, suggesting that particles become entangled through their interaction with this field, as opposed to viewing entanglement as a direct, passive ...
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39
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Canonical quantization of abelian vector field in $R_\xi$ gauge
I am trying to do the canonical quantization of an abelian vector field $A_\mu(x)$ in the $R_\xi$ gauge. So the gauge-fixing Lagrangian is given by $$ \mathscr{L}_{gf} = -\frac{1}{2\xi} (\partial_\mu ...
- 303
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Relationship of space-time to energy and momentum [closed]
After reading Noether's theoram and many other examples like objects tendency to follow its geodesics in spacetime makes conserved quantities like momentum etc meaningful so , are energy and momentum ...
- 1
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2
answers
308
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Trying to understand Reeh-Schlieder
In an attempt to understand the Reeh-Schlieder theorem, I am currently studying this paper, in which Witten provides a discussion using the formalism of quantum field theory. It is quite ...
- 17.7k
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4
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814
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Mathematical rigor behind renormalization [closed]
I struggle to understand how theories that are based on renormalization can be considered mathematically rigorous. I understand how renormalization works for non-abelian theories, through loop ...
1
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0
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57
views
Cross section normalization in $2 \to 2$ scattering
Consider Compton scattering $$p_1 + p_2 \to p_3 + p_4$$ in the laboratory frame. According to Quantum Field Theory and the Standard Model by Schwartz, the relation between the differential cross ...
- 486
2
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1
answer
93
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Gauge dependent mass definition in perturbation theory
Let's say we describe an unstable particle using perturbation theory. Then we have a non-zero decay width, which we say $\Gamma$. Now, if we define mass to be the pole of the propagator, we get
$$
\mu^...
- 586
1
vote
1
answer
98
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About Cutkosky cutting rule
I am working on a problem about Cutkosky’s cutting rule in Matt D. Schwartz’s Quantum Field Theory and the Standard Model. The problem asks us to show that the imaginary part of the amplitude is given ...
- 364
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votes
1
answer
132
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Interpretation of real scalar field, its propagator and causality [duplicate]
It seems this has been discussed here previously (e.g this and this post), but I still feel uneasy. Essentially, I think it all boils down to the popular interpretation of the scalar field operator in ...
- 1,158
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answers
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Why do interpretations of quantum phenomena focus on QM rather than QFT?
After reading a number of posts here in the last few years I'm left wondering why most questions about the interpretation of quantum phenomena relate to quantum mechanics rather than the more modern ...
- 1,390
2
votes
1
answer
109
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Expressing Feynman Integrals Using Schwinger Parameterization
I am trying to practice the techniques given in the book "Feynman Integrals: A Comprehensive for Students and Researchers," by Stefan Weinzierl (preprint). I am getting stuck on one point ...
0
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102
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Where do experiments enter the renormalization procedure? [duplicate]
I'm studying the renormalization of scalar quantum field theories ($\lambda\phi^4$ in particular). I'm considering renormalization by counterterms with the old non-Wilsonian interpretation of ...
- 864
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156
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Structure of Higgs potential
The Higgs potential is written as
$V(\phi) = -\mu^2 |\phi|^2 + \lambda^2 |\phi|^4$,
where $|\phi|^2 = \phi^\dagger \phi $ and $ \phi $ is a complex scalar doublet.
My question is: why do we not ...
- 51