All Questions
Tagged with renormalization quantum-electrodynamics
187
questions
-2
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0
answers
64
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QED with massless fermions
Consider QED such that physical mass of fermions vanishes. Is it true that their bare mass also vanishes?
- 2,226
16
votes
3
answers
3k
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Why is finding a mathematical basis for the fine-structure constant meaningful?
I was reading QED by Richard Feynman and at the end he mentions that:
There is a most profound and beautiful question associated with the observed coupling constant, $e$ – the amplitude for a real ...
- 169
3
votes
0
answers
74
views
Charge Renormalization in Abelian Gauge Theory under General Gauge Fixing Conditions
In scalar QED or fermionic QED, the relationship between bare quantities (subscript "B") and renormalized quantities is given by
$$
\begin{aligned}
A^\mu_B &= \sqrt{Z_A} A^\mu\,, \quad \...
- 51
1
vote
0
answers
55
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$Z_1=Z_2$ and its relation to vertex renormalization in QED
I have been working on the full renormalization of scalar QED with self-interactions, following the steps of Schwartz’s treatment on spinor QED (Chap 19). I have 3 main questions regarding this:
Need ...
- 162
2
votes
1
answer
69
views
Why is $F_1(0) = 1$? (form factor in QED)
In section 6.2 in Peskin and Schroeder (P&S) on vertex corrections, it is shown (eq 6.34) that the physical charge of the electron is given by $eF_1(0)$ (as shown by comparing the nonrelativistic ...
- 863
3
votes
2
answers
129
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Some integrals in QED Renormalisation
I am currently leaning the renormalisation of QED and I have met some tricky integral that seems unsolvable. The integrals are shown in Quantum Field Theory and the Standard Model by Schwartz, page ...
- 81
3
votes
1
answer
55
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Renormalisation in quantum optics
When reading about QED in QFT books, renormalisation seems to be essential to get results eventually. It also seems absolutely necessary even for low energies, since the internal lines lead to ...
- 1,831
0
votes
0
answers
117
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Looking for a graph of the running of the electron mass
Is there a graph somewhere showing how the electron mass changes with energy due to renormalization up to around the Planck scale - assuming that the pure standard model is always valid (thus no GUT, ...
- 727
1
vote
1
answer
64
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Charge renormalization choice in QED
In the lectures on QFT I'm following we define the renormalized QED Lagrangian as
$$\mathcal{L} = \dfrac{1}{4} (F_0)_{\mu\nu} (F_0)^{\mu\nu} + \bar{\psi}_0 (i \bar{\partial} - (m_0)_e) \psi_0 - e_0 \...
- 1,613
1
vote
0
answers
65
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Mass, field renormalization in QED
I am trying to understand the formula for mass and field renormalization in QED from the book Gauge theory by Bohm, Denner, pp $202$. They use renormalized perturbation to rewrite the Lorenz gauge ...
- 534
7
votes
1
answer
1k
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Why does Lamb shift renormalization not affect decay rate?
As a preface, I know there are "more" correct ways to calculate the Lamb shift and decay rate through full blown QED, but this is what's most familiar with me, so I would appreciate an ...
- 303
0
votes
0
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105
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Is QED asymptotically free in lower dimensions?
It is well-known that QED (=quantum electrodynamics) is NOT asymptotically free in spacetime dimension $4$.
However, I wonder if it becomes asymptotically free in lower dimensions, such as $2+1$ ...
- 1,669
0
votes
1
answer
217
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Coupling renormalization $\lambda\phi^4$ vs QED
I have some doubts regarding the allegedly different procedures used in $\lambda\phi^4$ and QED.
First of all, I am more familiar with bare perturbation theory (no counterterms), so I would be ...
- 1,989
-1
votes
1
answer
65
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Trouble with loop calculations
I was trying to do loop calculation. I have done chapter 6 and 7 of Peskin and Schroeder which deals with one loop correction to electron vertex function and vacuum polarization. But I don't feel very ...
2
votes
0
answers
76
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Lorentz invariance
In QED loop renormalization, Lorentz invariance is often used to express the possible momentum-dependence of the propagators.
For example, the propagator corresponding to the fermion loop is
$$ie_0^2 \...
- 138