Effective models for excitons in carbon nanotubes
  We analyse the low lying spectrum of a model of excitons in carbon nanotubes. Consider two particles with an attractive Coulomb self-interaction, placed on an infinitely long cylinder. If the cylinder radius becomes small, the low lying spectrum is well described by a one-dimensional effective Hamiltonian which is exactly solvable. 
Horia D. Cornean, Pierre Duclos, Benjamin Ricaud