  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.
