We investigate an operational description of identical noninteracting
particles in multiports. In particular we look for physically motivated
restrictions that explain their bunching probabilities. We focus on a symmetric
3-port in which a triple of superquantum particles admitted by our generalized
probabilistic framework would bunch with probability 3/4. The bosonic bound of
2/3 can then be restored by imposing the additional requirement of product
evolution of certain input states. These states are characterized by the fact
that, much like composite systems, their entropy equals the sum of entropies of
its one-particle substates. This principle is however not enough to exclude the
possibility of superquantum particles in higher-order multiports.Comment: 6 pages, comments welcom