Interacting like charges in Landau levels: Planar geometry, symmetries, and effective quasiparticles

We consider a system of two interacting particles with like but unequal charges in a magnetic field in the planar geometry. We construct a complete basis of states compatible with both the axial symmetry and magnetic translations. The basis is obtained using a canonical transformation that generates effective quasiparticles with modified interactions. We establish a connection of this transformation with the SU(2) algebra and make use of the SU(2) Baker-Campbell-Hausdorff formulas for evaluating the interaction matrix elements. We calculate analytically the eigenenergies of the problem (Haldane pseudopotentials) in the first few Landau levels for a relatively wide class of interaction potentials.