Aharonov-Bohm effect on exciton absorption of perpendicular light in carbon nanotubes

The Aharonov-Bohm effect on optical absorption of light polarized perpendicularly to the tube axis in semiconducting carbon nanotubes is studied by taking account of exciton and depolarization effect in an effective-mass approximation. The magnetic-flux dependence of the excitation energy is weak and quadratic around zero in contrast to the linear dependence for light polarized parallel to the axis.