Fano resonance spectra for the G band in metallic carbon nanotubes are
calculated as a function of laser excitation energy in which the origin of the
resonance is given by an interference between the continuous electronic Raman
spectra and the discrete phonon spectra. We found that the second-order
scattering process of the non-zero q electron-electron interaction is more
relevant to the continuous spectra rather than the q = 0 first-order process
because the q = 0 direct Coulomb interaction vanishes due to the symmetry of
the two sublattices of a nanotube. We also show that the RBM spectra of
metallic carbon nanotubes have an asymmetric line shape which previously had
been overlooked.Comment: 5 pages, 5 figures, submitted to Physical Review Letters on February
4, 201
