All Questions
Tagged with scattering quantum-electrodynamics
98
questions
-2
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1
answer
59
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What is the energy of a photon in an electron-muon scattering?
Currently I am reading about this process in an Introduction to Quantum Field Theory by Peskin and Schroeder (pages 153-154). It should be mentioned that they are working in a center-of-mass (CM) ...
- 41
0
votes
1
answer
47
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Elastic scattering and conservation of spin
I am trying to understand conservation of spin in QED elastic scattering in these nice notes (VJ Martin, Particle Physics, Spring 2012, University of Edinburgh): https://www2.ph.ed.ac.uk/~vjm/Lectures/...
- 184
0
votes
1
answer
423
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Is Feynman's Compton scattering diagram the same as the one in most books?
Feynman used the following Compton scattering diagram:
Whereas most books use this diagram in their derivation:
Is there a way to relate the two? Feynman's diagram makes more sense to me ...
- 187
2
votes
0
answers
51
views
An S-matrix description of the photoelectric effect?
As is well known, the photoelectric effect is an experimental phenomenon that had enormous historical importance for the emergence of the concept of photons and quantum mechanics itself. As is well ...
- 1,640
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0
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46
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Definition of (Differential) Scattering Cross Section in QED
In QED we like to define the (differential) cross section for a scattering process as follows:
$$d\sigma \ \dot= \ \frac{w_{fi}dN_f}{|j_{inc}|}\tag{1}$$
where $w_fi$ is the probability of transition ...
- 4,577
0
votes
0
answers
63
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Interpreting Feynman diagram of Coulomb scattering of positron
I am trying to understand Coulomb positron scattering. This course explains that:
Here the incoming state is in the future and is to be interpreted as a negative-energy electron of four-momentum $-...
- 132
3
votes
1
answer
273
views
Are QED Feynman diagrams readable in any order?
I have somewhat of a basic question regarding QED Feynman diagrams. To expose my doubts let's take the Feynman diagram of the Compton scattering (at the second order) as an example:
With the solid ...
- 4,577
2
votes
0
answers
100
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How does QED describe the electromagnetic scattering between two neutral fermions?
Fermions with no electric charge may carry magnetic moments e.g., the neutron. Since particles with magnetic magnetic moments interact, they're expected to scatter off each other electromagnetically. ...
- 11.8k
0
votes
0
answers
50
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Amplitude of the process $q \bar q \rightarrow \tau^+ \tau^-H$
I want calculate the cross section of the process $q \bar q \rightarrow \tau^+ \tau^-H$, where the Higgs takes the $vev$. My question is: if the Higgs takes the $vev$ the amplitude of the process is ...
- 11
1
vote
0
answers
80
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Solving QED Feynman diagram with one vertex
I'm new to Feynman diagrams and I want to calculate the probability of electron and positron anihilating into one photon to show it is impossible. I know this can be shown easier with special ...
- 333
2
votes
1
answer
113
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CPT invariance and Soft Theorems
I am reading the paper IR Dynamics and Entanglement Entropy, written by Toumbas and Tomaras and I have a question on using the CPT invariance of the QED $S$-matrix elements in order to derive the ...
- 3,992
1
vote
0
answers
42
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Order of fields in scattering amplitude
Given the lagrangian
$$\mathcal L=-\dfrac{1}{4}F_{\mu\nu}F^{\mu\nu}+(D_{\mu}\phi)^*(D^{\mu}\phi)-M^2|\phi|^2+\bar\psi(i\gamma^{\mu}D_{\mu}-m)\psi.$$
I tried to compute some first order scattering ...
- 111
2
votes
1
answer
380
views
Confusion about scattering in QFT
When it comes to scattering in QED it seems only scattering cross sections and decay rates are calculated. Why is that does anyone calculate the actual evolution of the fields themselves like how the ...
user366596
4
votes
1
answer
607
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Why is compton scattering inelastic?
With Compton scattering the total momentum and the total energy of the photon electron system is conserved, so it has to be ELASTIC Collision/Scattering.
But an argument is that just because the ...
- 151
2
votes
1
answer
347
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Loop-Level Calculation and Renormalization Applied to a Real Interaction in QED
In QED, we are taught about the one-loop corrections and the counter-terms to the photon propagator, as well as the one loop corrections and the counter-terms to the fermion propagator. We are also ...
- 3,992