# Quantum tunneling

muser
I knew of this phenomena prior to , though prior to an e-mail amazon sent me I was unaware of what physicists called it.
I have a question regarding the proton demonstration in this clip. Is it possible the electroweak force is acting on the 'tunneling' proton?
If, as the commentator is suggesting the proton is imbued (momentarily) with enough energy to circumvent the strong force, where is the additional energy coming from? are there test which pinpoint the energy source and could someone provide a link.
also one last question. I remember reading somewhere that it would take vast sums of energy to overcome the strong force, how is a proton or any subatomic particle able to use the extra energy to perform this feat?
I understand the rules that govern the quantum world are different to those which govern ours, but conceptually I find it hard to fathom how a proton might process the additional energy.

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## Answers and Replies

per.sundqvist
I know that they use a model potential for the weak interaction like:

$$$V(r) = \left\{ \begin{array}{l l} -V_b & 0\leq r<a\\ \frac{Ze^2}{4\pi\varepsilon r} & r\geq a\\ \end{array} \right.$$$

so you could get a finite tunnelling probability into the nucleus (r<a). You could estimate it by the WKB approximation. The nuclear binding energy V_b is of MeV and transitions between quantum levels give gamma-radiation.

But in principle you should solve the quark-quark problem, since all particles in a nucleus are made up of quarks (p=uud etc). I guess its better to talk about overlap of quark wave functions here, rather than tunnelling? Personally Im not satisfied with the quark-quark model potential, that assumes the potential grows proprtionally with relative distance, since two protons far away would destroy each other (expode into particle-anti-particles) because of quark-quark interaction. And more sopisticated gluon tranfer models, including Feynman diarams etc. are to complicated in my opinion, at least to desribe tunnelling of protons into a nucleus...