[SOLVED] Particle Physics, perhaps a classification problem 1. The problem statement, all variables and given/known data How are the classes of particles classified? 3. The attempt at a solution Classes of particles should be bosons, leptons, hadrons and baryons. First, I had the idea that the particles are classified according to interactions to them i.e. gravity, weak, electromagnetic and strong nuclear interactions, respectively for from boson to baryon. However, problems have raised when questions have become about exchange particles (force carriers). For example, for gravity interaction = graviton, weak = bosons, electromagnetic = photon, and baryon = gluons. I have had the idea some of these particles belong also to a group of particles such as photon to gravity. I attached a table to illustrate my point. In this table, I have colour-coded the groups and particles of which I am unsure, such as groups of particles and classes of particles (Is groups of particles = classes of particles?). Please, feel free to comment.