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B Do W Bosons have a rest mass?

  1. Apr 10, 2016 #1

    OmCheeto

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    About 40 years ago, someone told me that free neutrons decay with a half life of around 14 minutes.
    About 10 years ago, I discovered that W bosons were involved, and that they are about 100 times as massive as a proton.

    Do W bosons really exist as "massive" particles for their very brief lifespan?
    Or is their mass merely derived from the energy equivalence equation, and no one really knows?

    Thanks!
     
  2. jcsd
  3. Apr 10, 2016 #2

    Vanadium 50

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    I don't think your two statements are in conflict. We determine the masses of many things - most unstable particles - through relativistic kinematics ("energy equivalence equation" is just a special case), But yes, the W has a rest mass.
     
  4. Apr 11, 2016 #3

    mfb

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    The "W bosons" in neutron decays are not real particles. They do not need to have the mass of real W bosons.
     
  5. Apr 11, 2016 #4

    Garlic

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    Also, it's good to know that most weak decays don't have enough energy to create a real (on shell) and massive W bosons, so only virtual (off shell) W bosons are created in the process.
    But the top quark is massive enough to create a real W boson in the decay process, which makes its decay a lot faster than other particles.
     
  6. Apr 11, 2016 #5

    OmCheeto

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    I think this is what I was really asking; "Is the W- Boson involved in free neutron decay real, or virtual?"
    And your's was the answer I was hoping for.
    It's sometimes difficult for laymen to determine from pop-sci articles when particles are real, and when they're virtual.

    Double thanks!
     
  7. Apr 11, 2016 #6

    Garlic

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    Double no problem
     
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