  We propose a dynamical model for state symmetrization of two identical
particles produced in spacelike-separated events by independent sources. We
adopt the hypothesis that the pair of non-interacting particles can initially
be described by a tensor product state since they are in principle
distinguishable due to their spacelike separation. As the particles approach
each other, a quantum jump takes place upon particle collision, which erases
their distinguishability and projects the two-particle state onto an
appropriately (anti)symmetrized state. The probability density of the collision
times can be estimated quasi-classically using the Wigner functions of the
particles' wavepackets, or derived from fully quantum mechanical considerations
using an appropriately adapted time-of-arrival operator. Moreover, the state
symmetrization can be formally regarded as a consequence of the spontaneous
measurement of the collision time. We show that symmetric measurements
performed on identical particles can in principle discriminate between the
product and symmetrized states. Our model and its conclusions can be tested
experimentally.
