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Questions about radiative decay modes

  1. Sep 16, 2008 #1
    Let's take for example the decay K+ -> pi+,pi0,gamma

    This can proceed via direct emission or inner bremsstrahlung. I have questions for each of these modes

    1. For inner bremsstrahlung, it is a final charged product that radiates, correct? In this case the pi+. What is causing the deceleration of the pi+ such that it radiates?

    2. Does direct emission only come from from virtual particles or can it come from (in this example) one of the 4 quarks in the final state?

    Thanks for any help in advance
     
  2. jcsd
  3. Sep 16, 2008 #2
    I don't think it's appropriate to talk about "deceleration" in this context. IB is simply a radiative QED effect.

    By definition, DE occurs before pions are fully formed. Fully formed pi0 is neutral and can't radiate, gammas emitted from fully formed pi+ are part of IB.
     
  4. Sep 16, 2008 #3
    So the DE photons come only from the virtual particles and IB from the fully formed ones? How do you differentiate between these two modes experimentally?
     
  5. Sep 17, 2008 #4
    IB is the dominant mechanism and DE is a tiny correction to that. IB width is easily calculated using QED, DE is much more nontrivial because you can't fully explain processes that go on during the decay of K in terms of virtual particles and perturbative QCD. I'm not an expert, but I'd imagine that spectra would be different.

    See this presentation, hope it helps

    http://www.lnf.infn.it/wg/vus/workshop07/Talks/Raggi.ppt
     
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