▎ 摘　　要

We examine the 1/N expansion, where N is the number of two-component Dirac fermions for Coulomb interactions in graphene with a gap of magnitude Delta=2m. We find that for N alpha >> 1, where alpha is graphene's "fine-structure constant," there is a crossover as a function of distance r from the usual three-dimensional Coulomb law, V(r)similar to/r, to a two-dimensional Coulomb interaction, V(r)similar to ln (N alpha/mr), for m(-1)<< r << m(-1)N alpha/6. This effect reflects the weak " confinement" of the electric field in the graphene plane. The crossover also leads to unusual renormalization of the quasiparticle velocity and gap at low momenta. We also discuss the differences between the interaction potential in gapped graphene and usual quantum electrodynamics for different coupling regimes.