# Tagged Questions

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, ...

41 views

87 views

### How to prove that identical particles are attracted or repelled in a given spin-s interaction theory?

Let's assume that we have integer spin interaction theory (EM field, linearized gravity, arbitrary gauge spin s theory). How to prove the consequence that in interaction theory with spin $s = 2n$ two ...
53 views

### diffraction from sphere solution

I want to solve a problem of plane wave diffraction by a large sphere. There is a formula that I found from papers, but I think needs numerical solution. please help me to solve it The formula is ...
86 views

### Why is number of collisions equal to number of scattered particles times number of scatterers?

In Landau, Lifshitz "The Classical Theory of Fields" $\S12$ "Invariant cross-section" the following is said1: ... according to the usual definition of the cross-section $\sigma$, the number of ...
84 views

### What limits of integration do Landau and Lifshitz use here?

In "Mechanics" book by Landau and Lifshitz, $\S18$ "Scattering", problem 7 on deducing the form of scattering field given the effective cross-section as a function of scattering angle an equation is ...
48 views

### scattering of light

How does the path of light become visible due to scaterring of light? According to me it will only tell the presence of colloidal particle but the book give the example of cinema hall projector and ...
288 views

132 views

### Optical Theorem ,how can experiment distinguish the unscattered wave from the forward scattered wave?

How can experiment distinguish the unscattered wave from the forward scattered wave? The Optical Theorem says the imaginary part of the forward wave determines the cross section for an initial ...
11k views

### Why can't we see gases?

I am not sure what causes gas molecules to be invisible.This question may look silly but I really want to know the story behind it.
115 views

I am trying to understand some points about the paradox, what I am doing is solving the for the step potential $$V = V_0 ~\theta(z)$$ I have two solutions $$\Phi_I = e^{ik_1 z} + r e^{-ik_1 z}$$ ...
409 views

The differential cross section of Rutherford scattering blows as $\theta\rightarrow 0$. People express this fact as "The Coulombic potential is of long range". But I am seeing the opposite: $\theta ... 1answer 559 views ### Eikonal approximation in QFT Does the eikonal approximation for calculating a scattering amplitude in QFT provide the exact result in the limit of$s\rightarrow\infty$at finite$t=0$($s$and$t$are the usual Mandelstam ... 2answers 430 views ### Lippmann-Schwinger Equation with Outgoing Solutions I'm reading about Green's functions and how the Lippmann-Schwinger equation eventually leads to the textbook expression for the form of wavefunctions in the far radiation zone after scattering by a ... 1answer 244 views ### A question about the energy of turning on and off interaction adiabatically in QFT I read a saying as follows: In a theory with no particles which decay and no bound states, the turning on and off of the interactions merely serves to limit the effective range of forces. In this ... 3answers 167 views ### How does a wave packet get scattered? Particles can be represented as wave packet. So how do particles get scattered? Waves superimpose on one another, they don't bounce off of on one another. It can be seen from picture there is a ... 2answers 556 views ### Why are neutrino and antineutrino cross sections different? Particularly in the case of Majorana neutrinos, it seems a little odd that the particle and antiparticle would have differing cross sections. Perhaps the answer is in here, but I've missed it: ... 0answers 102 views ### How do I determine resistivity from electron defects of high purity gold? I am trying to create a plot for the electrical resistivity of high purity gold from 1 K to 1000 K. I found gold's resistivity at 300 K using the Wiedemann-Franz Law based on thermal conductivity data ... 0answers 87 views ### String Vertex Operators in Light Cone Gauge I have a basic confusion about how to compute string scattering amplitudes in light cone gauge, using the operator formalism reviewed in GSW. I am familiar with the covariant gauge formalism, where I ... 1answer 80 views ###$\mathrm{d} \Omega_{CM}$for a$1\rightarrow 2\$ particle decay?

The differential solid angle is described in e.g. Srednicki's QFT text but only for the case of scattering. Because in the case of scattering it's defined with respect to the incoming three-momentum ...
162 views

### Allowed interactions in bosonic string theory

In a quantum field theory, only a finite set of interactions are allowed, determined by the Lagrangian of the theory which specifies the interaction vertex Feynman rules. In string theory, an ...
725 views

### Why must an integrating sphere be a sphere?

Why must an integrating sphere be a sphere? Why can't it be an integrating cube? What is the difference? Could I use a cube to measure total illuminance like an integrating sphere does?
116 views

### Scattering theory of Dirac equation in curved space-time in presence of a strong magnetic field

What is the exact solution of the Dirac equation in curved space-time in the presence of a strong magnetic field? The solution should be in momentum space for simplicity to calculate scattering cross ...