Scattering is a general term for several physical processes in which radiation of some sort changes direction due to an interaction with a particle. Scattering can be classified by the type of radiation (ie, electromagnetic, x-ray, neutron), or by the relative sizes of the wave and the particle (ie, ...
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Tree level QFT and classical fields/particles
It is well known that scattering cross-sections computed at tree level correspond to cross-sections in the classical theory. For example the tree level cross-section for electron-electron scaterring ...
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1answer
246 views
Phase shift for Scattering in radial potentials
given a radial potential in 3 dimension and its Schroedinguer equation
$ -D^{2}U(r) + \frac{l(l+1)}{r^{2}}+V(r) $ here D means derivative with respect to 'r'
then if we apply quantum scattering how ...
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1answer
116 views
What is the dominant interaction in elastic collision pi- + neutron -> pi- + neutron?
What is the dominant interaction in elastic collision pi- + neutron -> pi- + neutron? Is it strong nuclear interaction or electromagnetism?
Edit: sorry I meant to say "elastic". There is no matter - ...
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1answer
179 views
What is deep Fresnel region?
If I understand correctly, it has something to do with autocorrelation function, but can someone give me a definition or exact explanation?
In case of scattering, if you wish to analyze pattern with ...
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0answers
319 views
Raman Scattering and the Kramers-Heisenberg Formula
Using the words of the wikipedia article Raman Scattering:
The Raman effect corresponds, in perturbation theory, to the absorption and subsequent emission of a photon via an intermediate ...
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1answer
118 views
diffusion by an external potential in quantum field theory
I'm studying quantum field theory and I encountered some problems of diffusion of particles by an external potential. Until now I have to do with diffusion of the type particle-particle obtaining the ...
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1answer
473 views
What does the Rayleigh Phase Function tell us
I am working on some radiative transfer equations, and struggling as I'm fairly new to this field. I have read about the Rayleigh Phase Function which is:
$P(\theta) = \frac{3}{4}(1 + cos^2 \theta)$
...
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6answers
950 views
Why can we treat quantum scattering problems as time-independent?
From what I remember in my undergraduate quantum mechanics class, we treated scattering of non-relativistic particles from a static potential like this:
Solve the time-independent Schrodinger ...
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1answer
658 views
What is the Jost function in scattering theory?
What is the Jost function in scattering theory? Is it an operator or some kind of determinant? How is it obtained?
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2answers
788 views
How do you calculate the intensity of light around the focal point from a focused collimated beam of light?
Problem/Purpose of me asking this question to you people who know more than me:
So I'm doing a science project where I'm collimating a beam of light to a focus point in a light medium (water vapor or ...
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3answers
13k views
Why does the moon sometimes appear giant and a orange red color near the horizon?
I've read various ideas about why the moon looks larger on the horizon. The most reasonable one in my opinion is that it is due to how our brain calculates (perceives) distance, with objects high ...
6
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4answers
424 views
Far-field intensity from scattering of small particles
Howdy, I'm building a simulation for looking at the light field underwater. In order to verify my simulation, I'm looking for some data showing the far-field intensity that comes from single ...
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Phase shifts in scattering theory
I have been studying scattering theory in Sakurai's quantum mechanics. The phase shift in scattering theory has been a major conceptual and computational stumbling block for me.
How (if at all) does ...
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1answer
264 views
How do ideas of leading singularities and Grassmanian help in curing infrared divergences when calculating N=4 scattering amplitudes?
Broadly speaking how do ideas of leading singularities and Grassmanian help in curing infrared divergences when calculating N=4 scattering amplitudes? My understanding is that one gets infra red ...
19
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2answers
633 views
Covariant Description of Light Scattering at a fastly rotating Cylinder
Let us consider the following Gedankenexperiment:
A cylinder rotates symmetric around the $z$ axis with angular velocity $\Omega$ and a plane wave with $\mathbf{E}\text{, }\mathbf{B} \propto ...
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2answers
498 views
Calculation of the cross section
Why, when we calculate the total cross section, we make the average other initial states and the sum over final states?
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1answer
576 views
Electron/Photon Scattering
Hey guys,
I have a final tomorrow and I am going over some assignments. One of the questions from the assignment was:
A photon having 37 keV scatters from a
free electron at rest. What is the
...
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1answer
633 views
Fermi's Golden Rule
It is well known that to calculate the probability of transition in the scattering processes, as a first approximation, we use the Fermi golden rule. This rule is obtained considering the initial ...
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Scattering of light by light: experimental status
Scattering of light by light does not occur in the solutions of Maxwell's equations (since they are linear and EM waves obey superposition), but it is a prediction of QED (the most significant Feynman ...
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3answers
321 views
How do molecules vibrate after collision?
The difference between kinematics and dynamics that Grisha pointed to in his answer comes up in a similar but slightly more complicated case:
Consider (in 1D) two point-like particles connected by a ...
5
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3answers
468 views
List of Scattering Phenomena
While at lunch with my lab group we got into discussion of the different types of scattering phenomenon that we encounter in everyday life and physical experiments. We ended up listing about a dozen ...
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3answers
328 views
Where do atoms go after collision?
[I edited the question according to Mark's and Grisha's answers.]
Consider two point-like particles of equal mass colliding centrally in 2D. The final directions of the momenta of the two particles ...
21
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4answers
981 views
Why does the sky change color?
Why the sky is blue during the day, red during sunrise/set and black during the night?
