Being ejected from \(\psi\) of the non-transit particle means the transit particle is freed. Beyond \(\psi\), where \(x\gt x_a\), the transit particle and the non-transit particle, being of the same type, repel each other. An the ejected particle quickly gain light speed, \(c\).
Wait a minute! The same type?!
Yes, as in an electron cloud! Physically in space, a cloud, as the sum of individual particles' \(\psi\). In energy, \(\psi_n\) or \(E_n\) in shells or energy levels.
Have a nice day.
