Tunneling of the 3rd kind

We study a new kind of tunneling of particles through a barrier particular to quantum field theory. Here, the particles traverse the barrier by splitting into a virtual pair of particles of a different species which interacts only very weakly with the barrier and can therefore pass through it. Behind the barrier, the pair recombines into a particle of the original species. As an example, we discuss the case where photons split into a pair of minicharged particles. This process could be observed in experiments of the light-shining-through-a-wall type and may be used to search for minicharged particles in laboratory experiments.