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Photo integrity

  1. May 23, 2005 #1
    Here is the question I had trouble with it:

    How to prove that an isolated photon cannot split into two photons going in direction other than the original direction.

    I thought photon doesn't have mass, then

    energy = momentum.
    from momentum conservation law. If photon split into two part and travel in different direction, then it must have different mass (or at opposite direction).

    That's all I have for the time being.
    Thanks for the help.
  2. jcsd
  3. May 23, 2005 #2


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    [tex]p^{\mu}=p_{1}^{\mu}+p_{2}^{\mu} [/tex] (1)

    Workin' in Heaviside-Lorentz units,

    [tex] \omega=\omega_{1}+\omega_{2} [/tex] (2)

    [tex] \vec{p}=\vec{p}_{1}+\vec{p}_{2} [/tex] (3)

    Square (2) & (3) and use [itex] \omega=|\vec{p}| [/itex] (which is valid for all 3 photons).

    Denote the angle between the momenta of outgoing photons by [itex]\theta[/itex]

  4. May 23, 2005 #3
    Great, but what are the p^u, w and p?

    I guess
    w = w1 + w2 is the energy conservation
    p = p1 + p2 is the momentum conservation, and what is

    the first equation ?

  5. May 23, 2005 #4


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    Conservation of 4-momentum,what else...?That's where the other 2 eqns come from.

  6. May 23, 2005 #5
    thanks, Daniel
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