▎ 摘　　要

We show that graphene in a strong magnetic field with partially filled Landau levels sustains charged collective excitations-bound states of a neutral magnetoplasmon and free particles. In the limit of low density of excess charges, these are bound three-particle complexes. Some of these states are optically bright and may be detected in spectroscopy experiments, providing a direct probe of electron-electron interactions in graphene. The charged excitations can be classified using the geometrical symmetries-non-commutative magnetic translations and generalized rotations-in addition to the dynamical SU4 symmetry in graphene. From the SU4 symmetry point of view, such excitations are analogous to bound states of two quarks and one antiquark qq (q) over bar with four flavors. We establish a flavor optical selection rule to identify the bright states for experimental studies. Copyright (C) EPLA, 2010