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In our Comment we question the validity of the claim made by the authors of\cite{cc} that their solutions of the Dirac equation in an external {\emtime-dependent} electromagnetic field describe beams of electrons. In everytime-dependent field, no matter how weak, which has {\em infinite} timeduration, there is a continuous electron-positron pair creation andannihilation. Without the proper accounting for these processes, themathematical solutions of the Dirac equation are not directly applicable torealistic physical situations. In particular, the time evolution of the averagevalues $\langle x\rangle$ and $\langle y\rangle$ does not describe the electrontrajectory but the motion of some combination of the electron and positroncharge distributions with pathological properties (zitterbewegung).

Comment on "Nondispersive analytical solutions to the Dirac equation"