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Homework Help: Question about relativistic energy

  1. May 12, 2005 #1
    A pion at rest ([tex]m_pi = 273m_e[/tex]) decays to a muon (mass = 207[tex]m_e[/tex] and an antineutrino (mass = 0). Find the kinetic energy of the muon and the energy of the antineutrino in electron volts.

    How am I supposed to start this problem? ANy help would be great...thx!
  2. jcsd
  3. May 12, 2005 #2


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    If the muonic antineutrino has no rest mass,then his energy & rel.momentum vector in modulus are linked through

    [tex] E_{\bar{\nu}_{\mu}}=pc [/tex]

    The key point is that both energy (seen as the time component of the energy-momentum 4-vector) and relativistic momentum (seen as the space components of the energy-momentum 4-vector) are conserved.


    P.S.Einstein's formula is [tex] E^{2}=m^{2}c^{4}+\left|\vec{p}\right|^{2}c^{2} [/tex].
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