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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124 views

Are reflection and transmission coefficents real or complex?

Is it common practice to give reflection and transmission coefficients as the ratio of the respective waves with respect to the incident wave when written in complex form or real form? I have seen ...
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833 views

What is the range of validity of 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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1answer
46 views

Au, Ag nanoparticles plasmon peak position?

Is the interaction between metallic nanoparticles (~ 20 nm) and light in the UV-Vis-NIR range governed by Mie theory or by Rayleigh scattering theory? Where are the Au and Ag plasmonic peaks located? ...
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145 views

Poles for a particle scattered in a delta potential

I am working on problem a professor gave me to get an idea for the research he does, and have hit a point where I'm having a difficult time seeing where I need to go from where I'm at. I would also ...
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20 views

Tadpole-free condition

Tadpole-free is a very important condition for perturbative string theory (which is equivalent to the theory to be expanded around the "right" vacuum). For simplicity, let's consider closed string ...
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175 views

Quantum theory of light

What's the scattering matrix for a PBS (polarization beam splitter)? Is it just unitary? If one polarization never couples into another polarization (then there's a lot of zeroes in that 4x4 matrix) - ...
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499 views

At what angle does a single atom “reflect” a single photon?

Does this question make sense in the quantum world? Imagining a single photon (wave packet?) interacting with a single atom (its electrons etc) how do we currently describe/define the emitted photon ...
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31 views

scattering matrix superccurent density of states

while studying scattering formula for the supercurrent (Beenakker) I encountered that the density of states for discrete and continuous spectrum can be simultaneously described by taking $\epsilon\ ...
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36 views

A conjecture about the Møller operator

Consider the Møller operator $$ \Omega_+ = \lim_{t \rightarrow -\infty } e^{i H t } e^{- i H_0 t } , $$ Now, suppose a state $\psi $ is located far away from the potential $V = H- H_0$. I feel that ...
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75 views

What is the necessity of wave packet in studying matter wave?

I am new to this realm of physics. I have literally understood the matter wave, wave function; read the trapped electron in an infinite potential-well. But what I didn't understand is the concept of ...
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19 views

Differential Cross sections from amplitude scattering matrix

How can I get the differential cross sections from the amplitude scattering matrix, $S$ (2x2 matrix)? I've seen this in a Mie solution solver: Parallel Polarized Light: dCsdOp = $\frac{2}{\pi k} ...
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74 views

Forward-scattering off a potential well

In his book, James Binney writes the following: My question is what is the meaning of this expansion as $1+T$? I say this because you don't tend to consider the possible "paths" that a particle ...
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259 views

How to replace $T$-product with retarded commutator in LSZ formula?

I am reading Itzykson and Zuber's Quantum Field Theory book, and am unable to understand a step that is made on page 246: Here, they consider the elastic scattering of particle $A$ off particle $B$: ...
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3answers
75 views

Could the sky on a planet theoretically be any color?

The sky on the Earth is blue. Could the color of the sky on a planet with an atmosphere be of any color theoretically? Which colors are the most likely? I think it would be really awesome to have ...
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1answer
26 views

Why ingoing and outgoing impact parameters equal in elastic scattering?

Take the Rutherford scattering, as for example in this picture: What is the easiest way to show that the impact parameter "b" (see picture) is the same for the ingoing and outgoing trajectories? ...
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32 views

Scattering of slow neutrons

I've here a spectrum which was obtained from the scattering of slow neutrons on uran. But I'm not sure what I'm actually see there. Can someone explain the "scattering of slow neutrons"? Edit: ...
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1answer
66 views

Increase contrast on the image taken by CCD camera

I project a pattern on a reflecting object and I capture the reflected pattern (reflected via the object) using a CCD camera. However, the reflected pattern has a very low contrast (due to volume ...
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1answer
94 views

Is the plane wave model always valid in reflection and transmission?

my question is related to another one I asked, but I foolishly made that question about several things (experiment, computation, theory) at once so it was confused. I was talking to my boss about ...
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66 views

Photon propagation direction prediction possible after interacting with neutral hydrogen?

My current line of research deals a lot with hydrogen's Lyman-alpha emission and subsequent interactions of the Lyman-alpha photons with the surrounding hydrogen gas. My question is whether ...
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2answers
292 views

Classical Rutherford scattering (partial) derivation

I am having trouble answering the following question, please could you help! Thank you in advance for any assistance you can give. Consider classical Rutherford scattering of a particle with mass $m$ ...
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34 views

Deriving general boundary conditions from first principles for elastodynamic scattering

It seems that most of the relevant books only give the linear case and the rest say something along the lines of "here are common examples of boundary conditions." What are the most general boundary ...
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24 views

Angles in Born approximation Spherical Potential

I have a question concerning (in my opinion) strange notation that arose in both the book by Shankar and Sakurai in the same manner. Where i am very confused by them both seemingly using the same name ...
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1answer
109 views

What is the most accurate experimental confirmation of Rutherford's $\sin^{-4}\phi/2$ law?

What is the most accurate experimental confirmation to date of Rutherford's $\sin^{-4}\phi/2$ law, where $\phi$ is the scattering angle?
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23 views

How to write down the Lippmann-Schwinger equation for such a problem? [closed]

Suppose there are three particles, 1, 2, 3. Initially, particle 2 and particle 3 form a bound state. Particle 1 is free. Now we want to study the scattering of particle 1 against the 2-3 bound system. ...
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33 views

Space-like pion electromagnetic form factor

The 1986's publication "A measurement of the space-like pion electromagnetic form factor" (http://dx.doi.org/10.1016/0550-3213(86)90437-2) starts with: The pion form factor has been measured in ...
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3answers
149 views

How is the scattering length in 2d defined?

Scattering length is 3d is well-defined. In the literature, one can also see scattering length in 2d. How is it defined? Can we even generalize it to 1d?
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49 views

Derivation of the Lippmann-Schwinger equation

I was trying to understand the derivation of the Lippmann-Schwinger equation in Sakurai's Modern Quantum Mechanics, Section 6.1. Our teacher presented a much simpler derivation, similar to that on ...
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167 views

A question about the energy of turning on and off interaction adiabatically in QFT

I read a saying as follows: In a theory with no particles which decay and no bound states, the turning on and off of the interactions merely serves to limit the effective range of forces. In this ...
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1answer
23 views

Scattering Matrix of a Given Circuit - Microwave

This might be an easy question but I couldn't find it in our course book[Microwave Engineering, Pozar, 4th ed] or on internet. I have a homework and one of the questions asks me to find the S-Matrix ...
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631 views

Why can the Euler beta function be interpreted as a scattering amplitude?

The Wikipedia article on the Veneziano Amplitude claims that the Euler beta function can be interpretted as a scattering amplitude. Why is this? In another word, when the Euler beta function is ...
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17 views

QM scattering in a finite-sized box

Background Consider a non-relativistic particle in a one-dimensional box of length $L$ with (for definiteness) an attractive delta function at the origin: $H = \frac{P^2}{2m} -|c|\delta(x), \qquad ...
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2answers
76 views

Rainbow reflected on TV screen? (pic attached)

According to wikipedia, A rainbow is an optical and meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets... Given that we require ...
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18 views

Why we're using Rollnik type potentials in non relativistic scattering?

I'm studying non relativistic scattering theory and I just started the section relative to time independent scattering with one-particle potential. According to my lecture notes, a potential is ...
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1answer
20 views

Thomson scattering: radiation scattered in one direction or all directions?

I have a question about how Thomson scattering takes place. Say X-rays hit a bound electron in a crystal. (These electrons aren't "free", but the energy difference is so large that the scattering is ...
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28 views

X-rays scattered at righ angles of the incident ones: are they polarised?

Basic books dealing with the interaction of X-rays with matter ussually don't mention anything about the polarisation, but I read somewhere that X-rays scattered in matter are linearly polarized, ...
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1answer
35 views

Intensity of light wave penetrating soft tissue

I'm studying for a medical physics exam and I'm struggling with the following question: Calculate the fraction of energy which penetrates to a depth of 3cm in soft tissue for a beam of light at a ...
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33 views

intervalley optical phonon scattering

Is there any difference between modeling of intravalley and intervalley optical phonon scattering in solid?
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17 views

Relation between Compton Wavelength and Bound States

In their paper, "A Theory of Dark Matter" (http://arxiv.org/pdf/0810.0713v3.pdf), the authors in a section argue that if there is a massive dark matter particle $\chi$ which interacts via a force ...
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1answer
55 views

Concerning Mie scattering and phase function dependance

In general, scattering intensity is written as $I = I_{0} \frac{\pi a^2 Q_{sca} P(\theta)}{r^2 4 \pi}$ It is also written as $I = I_{0} \frac{i_1 + i_2}{2 k^2 r^2}$ I am sort of confused, given the ...
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3answers
1k views

Does the Breit Wigner formula apply to intermediate virtual particles?

Breit Wigner Formula describes the cross section for interactions that proceed dominantly via a intermediate particle (O*) A+B → O* → C + D: $$σ = \frac{2\Pi}{k^{2}}\frac{Γ_{i}Γ_{f}}{(E-E_{o})^{2} + ...
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22 views

Why organic materials' hole mobility is usually higher than electron mobility?

Most of OFETs, and in particular OTFTs, are p-type (p-channel devices), because the hole mobility is higher than the electron mobility in most organic materials (wikipedia). What is the reason for ...
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1answer
56 views

Boundary Conditions in a Step Potential

I'm trying to solve problem 2.35 in Griffith's Introduction to Quantum Mechanics (2nd edition), but it left me rather confused, so I hope you can help me to understand this a little bit better. The ...
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1answer
271 views

Are the Møller wave operators $\Omega_\pm$ related to $\lim_{t\rightarrow\infty}U(t)$ from field theory?

When we want to compute correlation functions $\langle\Omega|\,T\hat{\phi}(x_1)\ldots|\Omega\rangle$ in an interacting quantum field theory, we relate it to the free-field objects $|0\rangle$ and ...
3
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1answer
57 views

Scattering amplitude with on-shell virtual photon

Let's assume electron-electron scattering in QED in second order of perturbation theory. Then in the corresponding scattering amplitude there will appear photon propagator $$ D_{\mu \nu}(q = p_{i} - ...
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1answer
71 views

What is the energy of a Gaussian wave packet?

Suppose we have a potential barrier situation, that is $V(x)$ is zero everywhere except on the interval $[-a,a]$, where it is equal to some $V_0 > 0$. Introduce some Gaussian shaped wave packet to ...
5
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4answers
186 views

Particles scattering on fluids: breakdown of the effective continuum description

When does the macroscopic continuum description of a medium like a fluid break down? Say I'm interested in a scattering process of some particles with momentum $p$ and energy $E$ off a fluid of ...
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0answers
38 views

Elastic scaterring of neutrinos - Why does the electron neutrino dominate this channel

Could anyone add more detail to this statement off wikipedia In the elastic scattering interaction, a neutrino collides with an atomic electron and imparts some of its energy to the electron. ...
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1answer
18 views

Dynamic equations for propagation of light through dust

For smoothly inhomogeneous media light propagation can be modeled by Maxwell's equations with non-constant $\varepsilon$ and $\mu$. This allows to relatively easily model propagation in the medium ...
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70 views

A conceptual question about scattering theory in quantum mechanics

When defining the cross section, we use this formula $$ \psi_S = \frac{f(\theta,\phi)}{r} e^{ikr},$$ to prove this one $$ j_{out} = \frac{|f(\theta,\phi)|^2}{r^2} \frac{\hbar k}{\mu},$$ and then ...
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357 views

Expansion in solid spherical harmonics on the lattice

I'm interested in calculating scattering processes (e.g. Coulomb scattering of an electron beam by a single ion) in the context of lattice quantum field theory, and wonder if there is something like ...