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W particle and beta decay

  1. Sep 9, 2004 #1
    w particle and beta decay and muons

    How many w particles,at any instant in time, are there in one cubic metre of a mass of radioactive nuclei which undergo beta decay?
    And how fast do these w particles move on average?
    How many w particles are,at any instant in time, in the neighbourhood of a muon that strikes the upper atmosphere of the Earth?
    Last edited: Sep 9, 2004
  2. jcsd
  3. Sep 9, 2004 #2
    Short answer: None, unless some of those nuclei/muon have an energy greater than 80 GeV, in which case a real W might be produced (it decays away very quickly though).

    Longer answer: you're probably thinking of virtual particles "constantly being emitted and re-absorbed" by the nuclei/muon. Since virtual states are not observable, this is not a physically meaningful question.
  4. Sep 9, 2004 #3
    How many particles are emitted in a radioactive nuclei undergoing beta decay?? Uhhhh, if I'm not wrong isn't it dependent on how radioactive it is, how many becquerels stuff like that? I don't think the rate of radioactivity is constant right?

    btw, to zefram_c, are the W particles emitted by a quark during beta decay virtual or real?? Are if I'm not wrong W particles are pretty massive, is there something about the higgs mechanism which cause this mass? or is it something else?
  5. Sep 9, 2004 #4
    That's right, but the original question asked about W particles. I don't know how you define the rate (# decays/sec maybe), but the probability that a given nucleus decays per unit time is constant.
    They cannot be real in the decay of an isolated particle. However, if a nucleus that has an energy great enough scatters off another nucleus, it can emit a real W in the process.
    The Higgs mechanism is what generates the mass, yes. But the details of that should probably go in a different thread.
  6. Sep 10, 2004 #5

    In decay the W particles are virtual, yet as we all know they can become real when there is enough energy "around" that is used to give these virtual particles a legitimate reason to exist. Conservation of energy can be violated in QFT for a short while and this time period is determined by the Heisenberg-uncertainty principle between energy and time.


    and yes, the mass of the gauge bosons is acquired through interaction with the omnipresent Higgsfield after the spontanuous breakdown :eek: of symmetry of the QCD-vacuum (the U(1)-symmetry, right...)

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