Can destroy a real photon(mass on-shell) to create a pair massive particles?

  • #1
519
0

Main Question or Discussion Point

Please teach me this:
Can a real photon be destroyed to create a pair of massive particle-antiparticle?.It seem that if it can be,the conservation of energy-momentum is violalated?
Thank you very much in advanced.
 

Answers and Replies

  • #2
160
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Please teach me this:
Can a real photon be destroyed to create a pair of massive particle-antiparticle?.It seem that if it can be,the conservation of energy-momentum is violalated?
Thank you very much in advanced.
A single photon cannot make any pair of particle and antiparticle - you need atleast one more photon [tex]\gamma \gamma \rightarrow e^{+}e^{-}[/tex] as an example . And maybe even a mediator, like an electron.
 
  • #3
mathman
Science Advisor
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At sufficiently high energies (> 1.022 Mev) a single photon can interact with a nucleus (which is needed for momentum conservation) to form an electron-positron pair.
 
  • #4
970
3
Please teach me this:
Can a real photon be destroyed to create a pair of massive particle-antiparticle?.It seem that if it can be,the conservation of energy-momentum is violalated?
Thank you very much in advanced.
I never thought of that before.

Anyways, it seems one photon can only create other photons (or other massless particles), and no more than 3 of them.

So I think the following are possible:

[tex]\gamma \rightarrow \gamma+\gamma [/tex]
[tex]\gamma \rightarrow \gamma+\gamma+\gamma [/tex]

Actually, I don't think any of this is possible. You get the above only when you consider that the initial and final state have the same spacetime distance. When you also consider conservation of momentum, then you can't have anything.

So one photon cannot create anything.
 
Last edited:
  • #5
160
0
I never thought of that before.

Anyways, it seems one photon can only create other photons (or other massless particles), and no more than 3 of them.

So I think the following are possible:

[tex]\gamma \rightarrow \gamma+\gamma [/tex]
[tex]\gamma \rightarrow \gamma+\gamma+\gamma [/tex]

Actually, I don't think any of this is possible. You get the above only when you consider that the initial and final state have the same spacetime distance. When you also consider conservation of momentum, then you can't have anything.

So one photon cannot create anything.
Yes. It does not conserve symmetry.
 
  • #6
970
3
  • #7
970
3
I never thought of that before.

Anyways, it seems one photon can only create other photons (or other massless particles), and no more than 3 of them.

So I think the following are possible:

[tex]\gamma \rightarrow \gamma+\gamma [/tex]
[tex]\gamma \rightarrow \gamma+\gamma+\gamma [/tex]

Actually, I don't think any of this is possible. You get the above only when you consider that the initial and final state have the same spacetime distance. When you also consider conservation of momentum, then you can't have anything.

So one photon cannot create anything.
oops, I confused sines with cosines (that always trips me up).

So the real result should be that one photon can only turn into massless particles, and these massless particles must all be collinear in the same direction as the original photon.

So a photon can turn into any number of massless particles/antiparticles, but they all have to be colinear.
 

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