Questions tagged [scattering-cross-section]
A cross-section is the name given to a hypothetical unit of area (often in units of Barns) for measuring the probability of scattering events in particles collisions. DO NOT USE THIS TAG for a physical non-probabilistic cross-section of a macroscopic object.
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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) ...
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Fitting function to compton continuum of data measured by scintillator detector
I have measured the spectrum of $ \:^{60}$Co with an NaI-scintillator detector. Now I want to fit a function to the measured compton continuum. My idea was, that the measured counts are proportional ...
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Relative speed in unpolarized cross-section
In section 5.1 of Peskin and Schroeder, we are presented the computation of the amplitude for the $e^+e^-\to \mu^+\mu^-$ reaction and then the computation of the unpolarized cross section. After ...
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How can I calculate the cross-section of a $N+\pi \rightarrow N + \pi$?
In the same theme as my previous question, I have the diffusion process $$N+\pi \rightarrow N + \pi$$ where the Lagrangian for this theory is
$$L = \partial^\mu\psi\partial_\mu\psi^* - M²\psi\psi^*-\...
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How can I calculate the cross section in general?
How can I calculate the cross-section of a process with three possible Feynman diagrams? I usually see examples with only the scattering amplitude defined by the $t$ channel, but if the scattering ...
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Relation bitween Mandelstam Variables in three-body final state
What is the relation between Mandelstam variables in the three body final state?
There are 5 independent Mandelstam variables. What is the relationship between them?
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How to Express the Cross Section of a Three-Body Final State Scattering in Terms of Invariant Masses $s_{ij}$?
I'm working on calculating the cross section for a scattering process that results in three bodies in the final state. My goal is to express the cross section in terms of the invariant masses $s_{ij}$...
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Fermi theory cutoff from unitarity bound
Tree-level cross sections for processes described by Fermi theory behave like $\sigma $ $\sim$ $G_{F}^2 \cdot s$, where $G_{F}$ is the Fermi constant and $\sqrt s$ is the energy entering in the ...
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How to deal with the divergence in tree-level diagrams? where the propagator momentum is on-shell
Only consider the interaction term between electron Higgs and $Z$ boson
$$
\mathcal{L}_{h ff}=-\frac{Y_f v}{\sqrt{2}} \bar{\psi} \psi\left(1+\frac{h}{v}\right)
=-m_f \bar{\psi} \psi\left(1+\frac{h}{...
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Compton cross-section measure, 0 degrees
We are a group of undergraduate students currently doing a lab work to measure the Compton Cross-section, using a radioactive ${}^{22}$Na source.
The setup simply has the ${}^{22}$Na source decaying $\...
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Spinor-helicity formalism: relationship between 1 and 2 reference vector setups
The spinor-helicity formalism is usually set up so that for a massless vector boson (photon or gluon) with momentum $k$ an arbitrary reference momentum $p$ is introduced and the corresponding ...
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Incident flux in a plane wave
As mentioned in Nuclear Structure by Bohr and Mottelson
Flux of incident particles associated with waves normalized per unit energy is
$$(\rho v)_\text{incident channel} = p^2/(2\pi\hbar)^3$$
How does ...
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Highly relativistic electron scattering in thin plasma
I am curious about how extremely relativistic electrons (10s of GeVs to single TeVs) scatter when going through the interplanetary and interstellar medium, which is a thin plasma. I have read about ...
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Reciprocity theorem of reaction cross section
The reciprocity equation for reaction cross section reads
$$ka^{2}\sigma_{ab}=kb^{2}\sigma_{ba}$$
or
$$pa^{2}\sigma_{ab}=pb^{2}\sigma_{ba}$$
Here
$\sigma_{ab}$ is the total reaction cross section for ...
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Extending Quantum Treatment of Attentuation Coefficient
I was reading this document to understand the links between the attenuation coefficient and quantum scattering. Consider a beam of number density $\rho$ and velocity $v$ in the z direction. $I = \rho ...
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