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I How do neutrinos conserve angular momentum?

  1. Mar 16, 2016 #1
    I'm learning about beta decay and as I understand in beta decay we get:

    neutron → proton + electron

    And since all these have spin 1/2 we have that the conservation of angular momentum is not conserved.

    The neutrino with spin 1/2 is proposed to also exist in the process to solve this so that:

    neutron → proton + electron + neutrino

    But I don't understand how this conserves angular momentum since haven't you now gone from a spin 1/2 particle one side to three spin 1/2 particles the other side so the spin has changed by 1. Shouldn't the change in spin need to be zero to conserve angular momentum?
  2. jcsd
  3. Mar 16, 2016 #2


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    The angular momentum has not changed. You can couple three spin 1/2 to an overall spin 1/2 (simply couple two of the spins anti-parallel).
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