Universality of electron correlations in conducting carbon nanotubes

An effective low-energy Hamiltonian of interacting electrons in conducting single-wall carbon nanotubes with arbitrary chirality is derived from the microscopic lattice model. The parameters of the Hamiltonian show very weak dependence on the chiral angle, which makes the low-energy properties of conducting chiral nanotubes universal. The strongest Mott-like electron instability at half filling is investigated within the selfconsistent harmonic approximation. The energy gaps occur in all modes of elementary excitations and estimate