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Homework Help: Optical Theorem

  1. Jan 5, 2010 #1
    1. The problem statement, all variables and given/known data
    Hi. For the question given (attachment) where does the factor of 2PI in the function for sigma come from in the first step because I don't get it in my working for the first step.

    2. Relevant equations
    see attachment

    3. The attempt at a solution
    I got sigma (without the 2PI) by changing variable to t =cos theta, thus integrating between minus and plus 1

    and using m=n in the legendre polynomial,

    so I am wondering if the 2PI came from integrating over the phi dependence as we are dealing with scattering from a radial potential?

    I also need prodding in the right direction for the next step!

    Attached Files:

    • 14.JPG
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    Last edited: Jan 5, 2010
  2. jcsd
  3. Jan 6, 2010 #2


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    Science Advisor

    Yes, the 2pi comes from integrating over phi, and so there should be a 2pi in front of the integral sign in the last equation.
  4. Jan 6, 2010 #3
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