▎ 摘　　要

The spectrum of two-dimensional (2D) plasma waves in graphene has been recently studied in the Dirac fermion model. We take into account the whole dispersion relation for graphene electrons in the tight-binding approximation and the local-field effects in the electrodynamic response. Near the wave vectors close to the corners of the hexagon-shaped Brillouin zone we find low-frequency 2D plasmon modes with a linear spectrum. These "intervalley" plasmon modes are related to the transitions between the two nearest Dirac cones.