How to Handle Photon Interactions in Particle Physics?

[nhristov]

I'm just working on a particle physics assignment and seem to be a little stuck on one concept. I have a positron-electron to two scalar particles and a photon-photon -> electron-positron problem.
The issue I'm having with it is that the only way I really know how to handle them is with the casimir tricks, but the casimir tricks seem to be for when you have for example u'*gamma*u where u and u-bar are an incoming and outgoing fermion and gamma is a matrix.
Is there a different trick to handle the case for having incoming photons rather than an incoming fermion?

Wow, problem solved, I feel silly, antifermions have u-bar for incoming particles rather than outgoing, this is where my issue is. People of the future, read carefully.

 

[mark726]

Hello there,

I'm glad you were able to solve your problem! It's always important to carefully read and understand the notation and conventions being used in a problem.

To answer your question, there are indeed different techniques for handling particles and antiparticles in particle physics calculations. In the case of incoming photons, you can use Feynman diagrams to represent the interaction between the photons and the particles. The Feynman rules for photon interactions include conservation of energy and momentum at each vertex, and the use of propagators to represent the virtual particles involved in the interaction.

Another technique that can be used is the calculation of scattering amplitudes using quantum field theory. This involves writing down the relevant Lagrangian for the particles involved and using Feynman rules to calculate the amplitude for the given process.

I hope this helps and good luck with your assignment! Keep exploring and learning about particle physics, it's a fascinating field.