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Quick question on Fermi Golden Rule

  1. Feb 5, 2015 #1
    Adopted from my lecture notes, found it a little fishy:

    e7c84j.png

    Shouldn't ##\frac{dp}{dE} = \frac{E}{p}## given that ##p = \sqrt{E^2 - m^2}##. Then the relation should be instead:

    [tex]\frac{dp}{dE} = \frac{E}{p} = \frac{E}{\sqrt{E^2 - m^2}}[/tex]
     
  2. jcsd
  3. Feb 5, 2015 #2
    Yes, you are right but the problem tells you that B and C are massless. This means that the magnitude of their momenta is equal to their energies. In particular, conservation of energy tells you that ##E_B=E_C=E_A/2## and so ##p_B=p_C=E_A/2##, giving ##dp_B/dE=1/2##.
     
  4. Feb 5, 2015 #3
    And I suppose ##c=1##?
     
  5. Feb 5, 2015 #4
    Exactly.
     
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