All Questions
Tagged with scattering-cross-section renormalization
9
questions
1
vote
1
answer
185
views
On the renormalization condition of the QED vertex function
In any renormalizable theory, we exploit the so-called renormalization conditions to determine the finite part of the counter-term couplings (namely $Z_1, Z_2$, etc in QED). In the on-shell scheme, we ...
- 3,992
1
vote
0
answers
104
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Collinear Divergences and SCET (Soft Collinear Effective Theory)
Can someone elaborate on how to treat collinear divergences in massless fermionic theories, such as the massless QED? Some very basic words on where do we can find such divergences and how to cure ...
- 3,992
3
votes
1
answer
293
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Pretending photon has a small mass in soft bremsstrahlung
In Peskin and Schroeder chapter 6, on page 184 when discussing the infrared divergence problem in perturbative QED, the book says we can make the following equation
$$\tag{6.25} \text{Total ...
- 789
3
votes
1
answer
763
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Infrared Divergence in Quantum Field Theory
In Peskin and Schroeder's QFT book, on chapter 6, the book tell us how to deal with the Infrared Divergence (IR).
Here is the book's logic:
For the process of Soft Bremsstrahlung,
$$
\begin{aligned}
\...
- 1,421
1
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0
answers
80
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Peskin & Schroeder's QFT on page 200
On Peskin & Schroeder's QFT book page 200, in the second paragraph, the book said: "$\cdots$ by making the replacement $e\rightarrow e\cdot F_{1}(q^2) $. The cross section for the process $\...
- 1,421
3
votes
1
answer
304
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Renormalization group applied to a simple QCD problem
Consider page 551 of Peskin & Schroeder's book on QFT, where he is treating the process $e^{+}e^{-} \to \text{Hadrons}$. I have 3 misunderstandings regarding some lines of thought effected there:
...
- 1,742
0
votes
0
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294
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Contributions to final states in the optical theorem
Consider the use of the optical theorem for computing the imaginary part of the total forward scattering amplitude $\mathcal M(AB \rightarrow AB)$. Then the theorem tells us to compute
$$2 \text{Im} \...
- 3,569
4
votes
1
answer
1k
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Field-strength renormalization in physical amplitude
Let's consider a physical process in QED:
\begin{equation}
e^+ e^- \rightarrow \mu^+ \mu^-
\end{equation}
I have to calculate the $\hat{S}$ matrix element at $O(\alpha^2)$ (tree level + one loop ...
- 43
1
vote
1
answer
312
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Why IR divergences cancel by cross sections of next-to-leading diagrams?
I was reading QFT & Standard Model by Schwartz, Chapter 20 which is about IR divergences. He says that
IR divergences only cancel cross sections for processes involving different initial or ...
- 1,151