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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Rigorous definition of density of states for continuous spectrum

For operators with pure point spectra it is clear how to count number of states corresponding to a given eigenvalue - one can just calculate the dimension of eigenspaces. I am wondering how to do it ...
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1answer
106 views

Convergence of light by light scattering amplitude

Perhaps I'm too exhausted to see the answer of why the photon-photon scattering should contain no divergences. In Peskin and Schroeder page 320 we find that because of the Ward identity the ...
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1answer
111 views

Interactions and scattering length in Feshbach resonances

In the context of cold atoms, one can make use of the Feshbach resonance mechanism to alter the sign and value of the two-particle scattering length by applying and varying an external magnetic field. ...
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19 views

Particle interaction kinematics in lab frame

Attempting a question from a past paper on scattering kinematics, fixed particle mass $m$ is struck by another particle mass $m$ with kinetic energy $T$. By evaluating $s$, $t$ and $u$, and their sum ...
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0answers
14 views

Difference between 'merging' and 'matching' procedure

For combining scattering processes with different jet-multiplicities in the final state, higher order corrections and parton shower, merging/matching procedures need to be applied to avoid ...
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2answers
10k views

If blue light has a higher energy than red light, why does it scatter more?

As $E=hf=\frac{hc}{\lambda}$, blue light - with a smaller wavelength - should have a higher energy. However, it is the case that blue light scatters the most. Why is it that higher energy rays scatter ...
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0answers
55 views

Finding $\psi(0)$ using Schrodinger equation with potential $U(x) = q\delta(x)$

I am having some trouble answering the following question in my "Advanced Quantum Mechanics" course: Using the integral equation: $$\psi(x) = Ae^{ikx} + Be^{-ikx} - ...
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2answers
114 views

Compton Effect Explanation

Can someone brief me about Compton effect and why does this happen? I searched everywhere read a CERN article too but couldn't understand it.
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1answer
62 views

Issues of normalization & differential final state momenta in analysis of normalized differential quantum-field-theoretic probability of scattering

The normalized differential quantum-field-theoretic probability $dP$ of scattering is given by $$dP=\frac{|\langle f |S|i\rangle|^{2}}{\langle f|f\rangle\langle i|i\rangle}d\Pi,$$ where $|i\rangle$ ...
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1answer
42 views

Alternatives to scattering experiments

Scattering experiments have been a fruitful and efficient way to determine the particles that exist in nature and how they interact. What are some of the other experimental techniques used to ...
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1answer
19 views

Why do smaller wavelengths image particles more clearly when the particle size is already big?

Yesterday I scanned an ultrasound phantom that had cylindrical inclusions (1.5mm diameter). When I boosted the ultrasound frequency from 3MHz to 4MHz, these inclusions became much more clear. I ...
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1answer
42 views

Are asymptotic states in scattering experiments really momentum eigenstates?

In a typical collider experiment, two particles, generally in approximate momentum eigenstates at $t=-\infty$, are collided with each other and we measure the probability of finding particular ...
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13 views

Is it correct that the polarized scatter of a polarized light source is max. orthogonal to the light source?

First of all, is the statement above correct? And if so, is there a constant gradient, with no polarized scatter parallel to the polarized source up to fully polarized at 90 degrees?
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14 views

Stationary-state scattering process

In a stationary-state scattering process of an incoming plane wave, the outgoing spherical wave can be described by $\psi(\vec r) = e^{ikz} + f(\theta) \frac{e^{ikr}}{r}$. My question is, how is this ...
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1answer
136 views

Thomson scattering cross section: free electrons vs atoms

I am trying to find a reference for the Thomson scattering cross section difference between free electrons and atoms. I have always assumed that free electrons have a higher cross sections, but I can ...
3
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0answers
66 views

S-matrix and derivative interaction

I just read in some lecture notes that formally we can write the S Matrix as: $$S=T(e^{-\int_{-\infty}^{+\infty} H_{int}dt}) $$ Where $T$ is the normal product and $H_{int}$ is in the interaction ...
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0answers
26 views

Bremsstrahlung in body tissue

As far as I know, the intensity of the produced radiation from bremsstrahlung is proportional to: $$I \propto \frac{Z^2}{m^2},$$ where $Z$ is the atomic number, and $m$ is the mass of the particle. ...
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0answers
12 views

Deep Inelastic Scattering - electromagnetic current

When one tries to compute the deep inelastic scattering for the process: where $l$ is a lepton with incoming momentum $k$ and outgoing $k'$, $h$ is an hadron with momentum $P$, $q$ denotes some ...
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4answers
12k views

What is the difference between Raman scattering and fluorescence?

What is the difference between Raman scattering and fluorescence? Both phenomena involve the emission of photons shifted in frequency relative to the incident light, because of some energetic ...
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1answer
19 views

How does momentum transfer in light scattering relate to the object size?

The momentum transfer vector is defined as the difference between the incident vector and the scattered vector. In the case of coherent light scattering, the momentum transfer vectors can be ...
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1answer
34 views

Differential cross-section for a 2-particle process in the LAB frame

This should really be a straightforward calculation, but somehow, I keep confusing myself and failing over and over again. I did the calculation so many times that I don't even know what I'm looking ...
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0answers
13 views

Spinor helicity formalism - original reference?

The spinor helicity formalism is a modern technique widely used in scattering amplitude calculations nowadays. However, it is hard to find a reference for who first came up with the formalism. Maybe ...
3
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2answers
131 views

Why the cross section can be obtained directly from the stationary scattering states?

I'm currently studying scattering theory in the book Quantum Mechanics, Vol. 2 by Cohen-Tannoudji. In the book the author deduces that to find the number of particles detected far from the target at a ...
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1answer
40 views

Crossing Symmetry in Bhabha scattering and Moller scattering

Given the amplitude for a particular process, it may be possible to obtain the amplitude for another similar process by a so called crossing symmetry. I know there is a $s \leftrightarrow u$ crossing ...
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1answer
63 views

How does Compton scattering demonstrate particle over wave behavior?

Why is Compton scattering thought to demonstrate light's behavior as a particle over that as a wave. I'm interested in the thoughts at the time of Compton, but also how it contradicts current theory ...
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0answers
35 views

Physical poles in QFT scattering amplitudes?

In QFT, for instance in $\phi^3$ theory, the scattering amplitudes are said to be constrained to feature so called "physical poles" only. Consider generalized Mandelstam variables ...
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1answer
20 views

Relation between probability density and transmission probability of a wavefunction?

Problems I did on current densities in elementary quantum mecanics course gives the answer contains transmission coeffecients, I am wondering is there any relation among them.
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1answer
42 views

$e^-e^-\rightarrow e^-e^-$ scattering relative negative sign quick computation

In the QED scattering process $e^-e^-\rightarrow e^-e^-$ there are two possible diagrams in the tree level. If I label the momenta I have, $$e^-(k_1)\quad e^-(k_2)\quad \longrightarrow \quad ...
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1answer
41 views

1D Scattering Phase Shift (Finite Well) - Unphysical?

I am calculating the phase shift from a 1-dimensional potential well. This seems extremely simple, but I am just getting so confused by it. Let there be a potential well of depth $V_0$ and spatial ...
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0answers
48 views

Pion-pion scattering amplitude with an effective Lagrangian

I have to compute the scattering amplitude at tree level for the process $$ \pi^{a}\pi^{b} \rightarrow \pi^{c}\pi^{d} $$ with an interaction given by what is written in the square brackets of the ...
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1answer
21 views

Mie theory: Interpretation in terms of intensity

I'm trying to understand Mie theory. For this I'm reading the book "Absorption and Scattering of Light by Small Particles" by Bohren and Huffman. The derivation of the formulas is fine, but I'm stuck ...
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1answer
569 views

Eikonal approximation in QFT

Does the eikonal approximation for calculating a scattering amplitude in QFT provide the exact result in the limit of $s\rightarrow\infty$ at finite $t=0$ ($s$ and $t$ are the usual Mandelstam ...
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1answer
28 views

Scattering matrix independent of energy

In quantum mechanics the scattering matrix is often used, to connect the states on the left and right side over some region in the middle. In the trivial case, that the Hamiltonian in the middle is ...
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0answers
24 views

Showing the transmission coefficient is valid

In a semiconductor device, electrons accelerated through a potential difference of 7V attempts to tunnel through a barrier of width 0.5nm and height 10V. Assume the potential is zero outside the ...
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5answers
6k views

Why is the sky of the moon always dark?

Why is the sky of the moon always dark compared to the sky of the earth, doesn't it have day and night like earth?
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36 views

Lippmann-Schwinger equation and time dependence

Consider the Lippmann-Schwinger equation (LSE) $$ |\psi\rangle = |\phi\rangle + \hat{G}_0(\epsilon) \hat{V} |\psi\rangle \tag{1}$$ where $\hat{G}_0(\epsilon) = \frac{1}{\epsilon - \hat{H}_0 + ...
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1answer
39 views

Atomic radii for elements as hard spheres

In neutron scattering, the atoms in a system are considered as hard spheres. Where could I find the appropriate (reliable) values of the atomic radii consistent with this physical picture? Thank you ...
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0answers
21 views

Why isn't every magnetic neutron scattering peak a nuclear scattering peak as well?

Neutron diffraction is a well-established technique for determining the magnetic unit cell of magnetic materials. The idea is that nuclear scattering gives you peaks that correspond to the crystal ...
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1answer
112 views

Why do shiny surfaces reflect more light than other surfaces?

I'm an A-level student and I love learning new things in physics. A new concept that I learnt says that the reflection is due to the scattering of light by electrons in the material. I've got my ...
6
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1answer
146 views

Reflectionless potentials in quantum mechanics

Scattering on potential $$V(x) = -\frac{(\hbar a)^2}{m}\text{sech}^2(ax)$$ with 1D equation of Schrodinger is famous problem. It is dealt with in Problem 2.48 of Griffiths book or online here. It is ...
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2answers
46 views

Difference between scattering and refraction?

I while back I learnt that when light is incident on a dipole the dipole will scatter the light, and when it is incident on a material of a different refractive index then the light refracts. From the ...
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2answers
54 views

Wave-like description of Compton scattering and photoelectric effect

I have found in the wikipedia page for QFT the following statement: ... Although the photoelectric effect and Compton scattering strongly suggest the existence of the photon, it is now understood ...
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0answers
29 views

Why do vortices scatter at right-angles

I have been taking a course on non-perturbative physics and currently the teacher is away so I cannot ask him. In the lectures, he made the claim that a pair of vortices in the abelian-Higgs model ...
2
votes
1answer
117 views

Conditions to determine the Green's function for scattering phenomena

Consider the elastic scattering of particles by a potential $V$ in Quantum Mechanics. In the zone of influence of the potential the Hamiltonian may be written as $$H = H_0 + V,$$ being $H_0$ the ...
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0answers
118 views

I find there are two methods to calculate the amplitude in QFT. Is it equivalent? [duplicate]

I find there are two methods to calculate the amplitude in QFT. First method: Use LSZ reduction formula $$\langle p_1\cdots p_m;out|k_1\cdots k_n;in\rangle=\big(\frac{i}{\sqrt{Z}}\big)^{n+m}\int ...
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0answers
29 views

Light scattering - creating an atmosphere that a laser will be visible in

I need to show the beams of red, green, yellow and violet lasers 100mW Red + 40mW Green for a demonstration in a darkened room that holds 150 people. The room has sensitive fire alarms that use ...
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0answers
67 views

Question about Quantum Scattering and the Born Approximation in Griffiths Intro to QM

I am trying to follow Griffiths Intro to Quantum Mechanics 2nd edition, chapter 11 Section 4 on the Born approximation of scattering. My question is what exactly are the definitions of $\vec{r}$ and ...
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0answers
12 views

Light scattering and absorption in material

I would like to get your inputs on a way for measuring light characteristics (scattering + absorption) in a specific tissue. My aim is to compare characteristics at different wavelength vis and nir. I ...
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1answer
30 views

Normalization of states of continuos spectra with complicated boundary conditions

Let's consider the following Schrödinger equation: $$\psi''(x)+k^2\psi(x)=0$$ with the following boundary condition $$\psi(0)+a\psi'(0)=0$$ $k$ is supposed to be larger that $0$. This equation is ...
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14 views

Scattering in Higher Dimensions

In 2 dimensional scattering, if the scattering situation is reflexive about the beam axis then we can relate the differential cross section to the impact parameter via ...