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Homework Help: Collision of particles (relativity)

  1. Nov 18, 2008 #1
    1. The problem statement, all variables and given/known data

    An incident positron (e+) with rest mass m_e and with energy E strikes an electron (e−) at rest, also with rest mass me. They annihilate such that the liberated energy produces a top quark (t) and an anti-top quark (ṯ), each with rest mass of m_t.

    Find an expression for the minimum incident energy E of the positron that will allow this reaction to happen.

    2. Relevant equations

    E^2 = P^2*m^2 + m^2*c^4

    3. The attempt at a solution

    I know I'm supposed to use the center of mass reference frame somehow, but I don't really have any idea how that helps. Can somebody please point me in the right direction?

    Edit: I got it. Please ignore this post.
    Last edited: Nov 18, 2008
  2. jcsd
  3. Nov 20, 2008 #2


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    Just responding to "un-blue" this post in the list of threads.
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