  Three paradigms commonly used in classical, pre-quantum physics to describe
particles (that is: the material point, the test-particle and the diluted
particle (droplet model)) can be identified as limit-cases of a quantum regime
in which pairs of particles interact without getting entangled with each other.
This entanglement-free regime also provides a simplified model of what is
called in the decoherence approach "islands of classicality", that is,
preferred bases that would be selected through evolution by a Darwinist
mechanism that aims at optimising information. We show how, under very general
conditions, coherent states are natural candidates for classical pointer
states. This occurs essentially because, when a (supposedly bosonic) system
coherently exchanges only one quantum at a time with the (supposedly bosonic)
environment, coherent states of the system do not get entangled with the
environment, due to the bosonic symmetry.
