▎ 摘　　要

We investigate the dynamical breakdown of the chiral symmetry in the theory of Dirac fermions in graphene with long-range Coulomb interaction. We analyze the electron-hole vertex relevant for the dynamical gap generation in the ladder approximation, showing that it blows up at a critical value alpha(c) in the graphene fine structure constant, which is quite sensitive to many-body corrections. Under static random phase approximation (RPA) screening of the interaction potential, we find that taking into account electron self-energy corrections to the vertex increases the critical coupling to alpha(c) approximate to 4.9, for a number N = 4 of two-component Dirac fermions. When dynamical screening of the interaction is instead considered, the effect of Fermi velocity renormalization in the electron and hole states leads to the value alpha(c) approximate to 1.75 for N = 4, substantially larger than that obtained without electron self-energy corrections (approximate to 0.99), but still below the nominal value of the interaction coupling in isolated free-standing graphene.