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What is the W- boson in beta decay?

  1. Apr 26, 2004 #1


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    neutron => proton + W- => proton + electron + electron anti-neutrino

    What're the quarks composing W-? To convert a neutron to a proton, there would need to be the expulsion of a down anti-up pair. That would mean a tad bit of mass loss, how does this work?
  2. jcsd
  3. Apr 26, 2004 #2
    A d quark in the neutron emits the W- and becomes a u quark., but there are no quarks in the W. The W is called a gauge boson, and it mediates electroweak interactions between leptons. It's a distinct type of particle from a quark (which is a lepton).

    The photon is another example of such a boson, as are the Z, gluon, and graviton (if it exists).
  4. Apr 26, 2004 #3


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    So it isn't a meson (edit: wait, stupid question as it doesn't have quarks)? By mediating the electroweak interaction, do you mean it is emitted from the neutron and then splits into an electron and antineutrino? Is it as simple as that or more complicated? If it is complicated, don't bother yourself with explaining it here.

    Thank you.
    Last edited: Apr 26, 2004
  5. Apr 27, 2004 #4


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    It is as simple as that. In any case you can consider that the W is very massive, thus the emission violates energy preservation and thus it must decay in a very short time, inverse of the mass or so, to meet Heisenberg principle.
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