Quantum Monte Carlo study on electron-phonon coupling in monolayer graphene

In connection with recent experiments of angle-resolved photoemission spectroscopy (ARPES) on graphite, we theoretically study the interaction between electrons and in-plane optical phonons in monolayer graphene by a constrained quantum Monte Carlo simulation. At K point of Brillouin zone, a well-defined sharp quasiparticle (QP) peak is observed in the ARPES of undoped graphene, but this peak exists only in a small electron-phonon (e-ph) coupling regime. It is shown the QP dynamics is closely related to the electronic states, e-ph coupling, and doping level.