No such practice. probably more typical to think of as "mathematical description of particles"
Particles are not described in either/or fashion as you suggest. String theory describes particles as vibrations of extended strings; charge manifests as one type of vibration, mass as vibrational energy, and so forth.
The extended nature of such "particles" avoids the infinities assoicated with mathematical descriptions of behaviors assoicated with point particles. Coulombs law for example, kq1q2/r2 becomes infinite as the distance between two charges apporaches zero. Doesn't quite seem that two finite charges would repel at infinite force in a classical theory. On the other hand quantum confinement of such particles might conceivabley produce incredibly powerful repulsion, but that's where quantum theory may not work so well either...The Pauli exclusion principle can cover a situation like that.