Magnetoplasmons and SU(4) symmetry in graphene

We study magnetoplasmons or neutral collective excitations of graphene in a strong perpendicular magnetic field, which can be modelled as bound electron-hole pairs. The SU(4) symmetry of graphene arising from spin and valley pseudospin degrees of freedom is explored using Young diagrams to correctly predict the degeneracies of these excitations. The multiplet structure of the states is identical to that of mesons composed of first and second generation quarks.