All Questions
29
questions
6
votes
1
answer
249
views
Are Weinberg's soft theorems relevant when making predictions about collider physics?
In a seminal paper, Weinberg has shown that one can relate a $n \to m$ scattering amplitude to the $n \to m + k$ scattering amplitude that involves the same particle content plus $k$ additional ...
- 22.1k
1
vote
0
answers
34
views
Physical coupling as a measurable quantity
I have a question about Preskill's quantum field theory note. He want to argue that the renormalized coupling is something measurable.
First let me introduce some backgroud. Suppose the Lagrangian can ...
- 1,863
2
votes
0
answers
88
views
Did I understand RG correctly?
I am currently self-studying Renormalization Group (RG) in Condensed matter physics (in preparation for graduate school while I'm in Alternative Military Service).
While I'm writing bunch of ...
- 21
1
vote
0
answers
51
views
Choosing a renormalization point where the amplitude is not defined?
This lecture note goes through the renormalization of the s-channel one-loop correction to the four-point function $\Gamma(s,t,u)$ in $\lambda \phi^4$-theory. It uses Pauli-Villars regularization, ...
- 11
3
votes
1
answer
399
views
$\beta$-function of general $\phi^6$ in 3 dimensions
In 3-dimensions the $\phi^6$ interaction is renormalizable and the $\beta$-function can be found in many reviews in the $O(n)$ symmetric case, $V(\phi) \sim (\phi_a \phi_a)^3$ where $a=1,\ldots,n$.
...
- 312
2
votes
0
answers
107
views
Energy Renormalization and Vacuum Diagrams
I have been reading the lecture notes of Coleman's course on QFT. When developing scattering theory with the use of a cutoff function, he mentions that, in order to ensure that the free vacuum ...
- 3,915
0
votes
0
answers
42
views
How to expand the QCD loops in terms of infrared scale for matching with heavy quark effective field theory
According to Manohar:"argument applies almost without change to a practical example,the derivation of the HQET Lagrangian to one-loop."
on page 37 of the following paper on effective field ...
- 1,268
5
votes
1
answer
337
views
Confusions on QED renormalization
In many QFT textbooks, we usually see the calculations of vertex function, vacuum polarization and electron self-energy.
For example, one calculates the vacuum polarization to correct photon ...
- 995
1
vote
1
answer
323
views
Asymptotic freedom both in IR and UV
I am wondering if there are any (insightful) examples for models which exhibit asymptotic freedom both in the UV and the IR. I know it sounds odd, but if anyone has come across something like that, ...
- 1,323
9
votes
1
answer
893
views
On scheme dependence in QFT renormalization
I searched for the answer to my question quite a while and it seems nobody ever asked similar questions or it is written explicitly in any textbooks. The question is,
If physical parameters of any ...
- 546
2
votes
1
answer
951
views
One-loop corrections to vacuum polarization with a specific Lagrangian
I'm having some difficulties regarding this problem in QFT I'm doing to prepare for an exam.
For the following problem I consider the theory described by the Lagrangian:
$$\mathcal{L}=-\frac{1}{4}F_{\...
- 474
3
votes
1
answer
398
views
In relativistic QFT, is it ever possible that the bare mass be finite and equal to the physical mass?
In renormalization, one follows the philosophy that the bare mass is unobservable and could be infinite, and the physical mass comes from the pole of the two-point function. Is it possible that in any ...
- 26.8k
3
votes
1
answer
821
views
Question related to electric dipole moment via QFT
My question is related to the following post: Extracting Electric Dipole Moment from Matrix Element via Form Factor
There, it is said that the electric dipole moment (EDM) is giving by a term that ...
- 1,597
4
votes
0
answers
61
views
Does the background shift affects the renormalization group equations?
In Section 21 of "Quantum Field theory" by Mark Srednicki, it is shown that there are two equivalent ways to get the quantum action of the shifted field $\phi'= \phi-\tilde{\phi}$, where $\phi$ is the ...
- 41
1
vote
0
answers
72
views
Is the Standard Model fully renormalizable? [duplicate]
't Hooft showed that Yang Mills theory with spontaneous gauge symmetry breaking Higgs potential is still renormalizable.
Is the Standard Model fully renormalizable?
The potential issues to ...
- 4,336