We present first-principles calculations of the linewidths of low-energy quasiparticles in n-doped graphene arising from both the electron-electron and the electron-phonon interactions. The contribution to the electron linewidth arising from the electron-electron interactions vary significantly with wavevector at fixed energy; in contrast, the electron-phonon contribution is virtually wavevector-independent. These two contributions are comparable in magnitude at a binding energy of ~0.2 eV, corresponding to the optical phonon energy. The calculated linewidths, with both electron-electron and electron-phonon interactions included, explain to a large extent the linewidths seen in recent photoemission experiments.
@article{arxiv.0902.3638,
title = {First-Principles Study of Electron Linewidths in Graphene},
author = {Cheol-Hwan Park and Feliciano Giustino and Catalin D. Spataru and Marvin L. Cohen and Steven G. Louie},
journal= {arXiv preprint arXiv:0902.3638},
year = {2009}
}