Probability of particle to exceed C?

[julcab12]

Is there a small probability for a particle or a photon to appear slightly exceed the speed of light?

 

[MisterX]

Most physicists probably think this does not happen in reality. In [relativistic] QFT it is not possible. In non-relativistic QM there is such a non-zero probability of getting a particle to move faster than light but it is considered a failing of the theory.

 

[Nugatory]

but it is considered a failing of the theory.

Of course there is nothing surprising about a non-relativistic theory allowing faster-than-light travel - that's part of what being non-relativistic means.

 

[ddd123]

This is the closest you get to the idea in QFT: https://en.wikipedia.org/wiki/Propagator#Faster_than_light.3F

To sum up, it only happens for virtual particles. So it's the same thing as energy conservation being violated by them.