Using functional renormalization group methods, we present a self-consistent calculation of the true Fermi momenta k_F^a (antibonding band) and k_F^b (bonding band) of two spinless interacting metallic chains coupled by small interchain hopping. In the regime where the system is a Luttinger liquid, we find that Delta = k_F^b - k_F^a is self-consistently determined by Delta = Delta_{ 1} [ 1 + { g}_0^2 ln (Lambda_0 / Delta)^2]^{ -1} where g_0 is the dimensionless interchain backscattering interaction, Delta_{ 1} is the Hartree-Fock result for k_F^{ b}-k_F^a, and Lambda_0 is an ultraviolet cutoff. If { g}_0^2 ln (Lambda_0 / Delta_{ 1})^2 is much larger than unity than even weak interachain backscattering leads to a strong reduction of the distance between the Fermi momenta.
Categories: cond-mat.str-el