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Quantum tunnelling outside the light cone?

  1. Mar 22, 2012 #1


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    Zee's QFT in a Nutshell makes a short comment in the first chapter about the possibility of particles tunnelling outside their light cone - is there some probability that a particle could do this? I know the neutrino thing has been debunked as a faulty cable, but did not see this offered as an explanation - why not? i
  2. jcsd
  3. Mar 23, 2012 #2


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    No thoughts?

    I did find this site

  4. Mar 23, 2012 #3


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    BWV, Zee's book has an easygoing style, but can be hard to nail down in places. The function he's talking about is the Feynman propagator, which falls off exponentially outside the light cone with a characteristic distance equal to the Compton wavelength, ħ/mc. This does not represent a violation of causality or influences going faster than light. In fact when combined with the existence of antiparticles it's exactly what is necessary to avoid such problems. Take a look at a more careful treatment, such as Weinberg Vol I, Sect 5.2.
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