All Questions
Tagged with renormalization effective-field-theory
215
questions
2
votes
1
answer
114
views
What does it mean to "resum" the large logarithms?
I am struggling to understand the concept of resummation of large logarithms in QFT; from what I learnt so far the problem relies on the fact that if a full theory defined in the UV contains much ...
- 477
2
votes
1
answer
47
views
Why does integrating out microscopic degrees of freedom lead to the effective free energy rather than the effective energy?
In David Tong's lecture notes on statistical field theory, he considers the partition function of the Ising model and computes the effective free energy by integrating out the microscopic details of ...
- 23
0
votes
1
answer
70
views
Loops and UV divergences
I read when asked whether a force could only exist at a certain phase transition or high energy:
"I am not aware of a coupling that only exists at high energies or in a phase transition -- in ...
- 425
0
votes
0
answers
41
views
Why the coupling constant in context of different approaches has different energy dependence?
I know that in the language of renormalization group, the coupling constant in the Hamiltonian is dependent of energy, for example in condensed matter physics, of band width. So, we can do a 'poor man'...
- 51
5
votes
1
answer
125
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Why do we rescale momenta after integrating out high momenta in Wilsonian renormalization?
In Section 12.1 of Peskin & Schroeder they motivate Wilson's approach to renormalization by asking how a quantum field theory changes after changing the momentum scale. To answer this they start ...
- 3,350
2
votes
1
answer
147
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Derivative interactions in the Wilsonian renormalisation Group
I am currently working through some basic renormalisation group problems, and have come to one about derivative interactions. It has been a while since I have studied QFT formally so bear with me ...
- 90
3
votes
1
answer
189
views
What is the physical meaning of the counterterms we add in Lagrangians?
I have a probably very silly question. Please help me with it:
Say we consider the QCD Lagrangian. All of it's terms involve various fields. Now this Lagrangian can simply be called the Lagrangian of ...
- 306
1
vote
0
answers
64
views
Reference request scale anomaly
Can anyone recommend some books, notes and review-oriented papers on scale anomaly, with a view towards its relation to renormalization? Such as an anomaly perspective on RG, Callan-Symanzik equations ...
1
vote
0
answers
48
views
What is the interpretation of the $\beta$ and $\gamma$ functions in the renormalization group?
Let $M$ be a renormalization/momentum scale, $\lambda$ a coupling, $G^{(n)}$ the $n$-point Green's function, $Z$ the field strength, and $\Lambda$ a momentum cutoff.
When studying the renormalization ...
- 3,350
0
votes
1
answer
114
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Renormalization group equation, the Callan-Symanzik equation, and renormalization group flow
I am learning about the renormalization group and I am getting confused on some terminology.
For the massless $\phi^4$ theory the Callan-Symanzik equation is:
$$\big[ M \frac{\partial}{\partial M} + \...
- 3,350
0
votes
1
answer
68
views
Is the magnitude of the $\beta$ function important?
I am currently studying the renormalization group in quantum field theory and have gotten up to computing the $\beta$ function perturbatively . While I only have a basic understanding of it so far, ...
- 3,350
1
vote
1
answer
88
views
Problem solving for Wilsonian Effective Action
I'm currently doing some basic questions on renormalisation group, but I've ran into a wall when it comes to one particular step in an answer. The question is as follows:
This problem is a toy model ...
- 90
5
votes
3
answers
271
views
Triviality of $\phi^4$ theory, is it settled now (2024)?
According to the answer on
question 364576
this should be settled. But after looking for clear statements of the current situation on triviality of $\phi^4$ theory, I'm still not sure, because:
In ...
- 4,913
3
votes
1
answer
102
views
Question about RG from QFT perspective, in particular Weinbergs book
This must be fairly basic I fail to understand. According to Weinberg, QFT Vol2, Ch.18 (The preamble)
When we replace bare couplings and fields with renormalized couplings and fields defined in terms ...
- 368
5
votes
1
answer
205
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Wilsonian RG in QFT: what is the difference between renormalized and bare couplings?
I want to understand the relation between the Wilsonian RG and the usual QFT RG approach. Several questions have been asked, such as this and many others, yet I don't find a conceptual answer to what ...
- 1,989