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1 vote
1 answer
37 views

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 ...
Rafael Grossi's user avatar
0 votes
0 answers
268 views

Addition of four-momenta in scattering amplitude of nucleon-anti-nucleon pair in scalar Yakuwa theory

Intro I'm studying QFT using David Tong's lecture notes. In section 3.5 on examples of scattering amplitudes in scalar Yukawa theory, the scattering amplitude $A$ of a nucleon-anti-nucleon scattering ...
coffee945's user avatar
6 votes
1 answer
2k views

How to derive the Klein-Nishina formula from the Dirac equation?

I'm looking for the simplest demonstration of the Klein-Nishina formula, from the Dirac equation without the field described as a quantum operator: https://en.wikipedia.org/wiki/Klein%E2%80%...
Cham's user avatar
  • 7,592
1 vote
2 answers
244 views

Feynman amplitude and tensor 4-vector multiplication (muon neutrino-electron scattering)

In the calculation of the Feynman Amplitude for the muon neutrino-electron scattering (in the Charged Current way from W boson), or $e + \nu_\mu \rightarrow \nu_e + \mu$ (considering the 4-momentum ...
Marcos's user avatar
  • 15
0 votes
1 answer
59 views

From infinitesimal momentum volume to infinitesimal rapidity & tranverse momentum

I'm trying to derive a relationship given in a paper which is used to obtained a differential cross-section distribution in function of rapidity and transverse momentum of final state particles, $$ \...
Pierre's user avatar
  • 125
4 votes
1 answer
400 views

Gram determinant for the $2\to 3$ scattering cross-section

I'll repeat the part of my previous question regarding the topic: There is a book of Byckling and Kajantie, "Particle kinematics", discussing in particular (Chapter V) the kinematics of the $2\to 3$ ...
Name YYY's user avatar
  • 8,901
0 votes
1 answer
852 views

Relativistic Scattering

When we work out the relativistic general two-body scattering in the CM frame (like two elementary particles producing two other P1 +P2 -P3 -P4) , the cross section is proportional to absolute final ...
Patrick's user avatar
  • 1,885
2 votes
1 answer
361 views

Is this statement correct or incorrect: Moving objects undergo length contraction because they appear in space-time cross-section

Why or why not? This is closely related to another question I posited here, Does it make sense to say that objects moving at relativistic velocities appear in space-time cross-section? What I mean ...
udrv's user avatar
  • 10.4k
2 votes
3 answers
367 views

Does it make sense to say that objects moving at relativistic velocities appear in space-time cross-section?

Let object A move at relativistic velocity relative to a frame O. In 4D space-time (Minkowski diagram) the space view of O at any given moment of its own time is a space-like hypersurface (hyperplane, ...
udrv's user avatar
  • 10.4k
0 votes
0 answers
91 views

Inelastic cross section derivation

I am trying to derive the inelastic cross section (the mass changes). I looked up the elastic derivation on Peskin's book (are there any alternatives?): $$d \sigma = \frac{1}{2 E_a 2 E_b \left| v_a-...
user1581390's user avatar
17 votes
3 answers
6k views

Is the total cross section a Lorentz Invariant?

In Peskin and Schroeder's book (P&S), on the botton of page 106, the authors say that the total cross section transforms as its only non-invariant factor, namely: $$ {1 \over E_{A} E_{B} |v_A - ...
Forever_a_Newcomer's user avatar
3 votes
2 answers
1k views

How do particle scattering cross sections scale with energy in colliders?

How do particle scattering cross sections scale with energy in colliders? Particularly photons, electrons, protons, and gold or lead nucleii? (If necessary, break this into four separate questions.) ...
Jim Graber's user avatar
  • 5,759
17 votes
1 answer
3k views

Cross-section in relativistic limit: Fermi's golden rule still valid?

In order to calculate the cross-section of an interaction process the following formula is often used for first approximations: $$ \sigma = \frac {2\pi} {\hbar\,v_i} \left| M_{fi}\right|^2\varrho\...
Chris's user avatar
  • 273