  Non-dispersive wave packet for massless fermions is formulated on the basis
of squeezed coherent states that are put in a form of common eigenfunction for
the Hamiltonian and the helicity operator, starting from the Dirac equation.
The wave packet thus constructed is demonstrated to propagate at a constant
velocity as that of light. This explicit expression of wave packet for the
massless fermions can facilitate theoretical analysis of problems where a wave
packet is of formal significance. Furthermore, extensive wave packet may result
in a superluminal velocity statistics if determined from the time-of-flight
measurement, as recently done on muon neutrinos, when a threshold particle flux
or energy transfer, which is eventually referred to the propagation of wave
packet, to invoke a detection event is assumed.
