How Can We Derive the Wavelength Sum Formula in Electron/Positron Annihilation?

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The discussion focuses on deriving the wavelength sum formula for photon emissions during electron-positron annihilation, specifically L1 + L2 = Lcompton(1 - cos(theta), where theta is the angle between the emitted photons. Participants suggest using conservation of energy and momentum, emphasizing the importance of drawing a clear diagram to visualize the problem. There is a consensus that the problem is complex and may require advanced understanding of 4-momentum conservation. The conversation highlights the need for a solid grasp of relevant physics concepts to tackle this college-level problem effectively. Overall, the discussion underscores the intricacies involved in applying relativity to particle physics scenarios.
Feynmanfan
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Well, I've been trying to figure out how to prove that when a positron and an electron annihilate and two photons are produced, the addition of their wavelengths equals

L1+L2=Lcompton(1-cos(theta)) where theta is the angle that separates both photons.

It's a relativity problem I guess. I keep trying E^2=Eo^2+c^2p^2 and other formulae but get no result.

Thanks for your help
 
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What is L?
 
I think he means lambda.
 
Who's wavelengths are u referring to...?Draw a diagram (not the Feynman diagram,it's useless) and use conservation of 4 momentum...

Daniel.
 
dextercioby said:
Draw a diagram (not the Feynman diagram,it's useless) and use conservation of 4 momentum...
Just in case the Original poster hasn't learned 4 vactor yet...

here is another way to approach this problem:
Use conservation of energy and momentum...
the algebra might be a little bit messy, this is college level problem, don't expect you can finish it in 10 minutes
 
He's Feynmanfan,he SHOULD know everything about Feynman diagrams & 4momentum conservation.

:wink:

Daniel.
 
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