Bridging the gap between numerics and experiment in free standing graphene.

We report results of large scale quantum Monte Carlo (QMC) simulations of graphene. Using cutting-edge algorithmic improvements, we are able to consider spatial volumes, corresponding to 20808 electrons, that allow us to access energy scales of direct relevance to experiments. Using constrained random phase approximation (cRPA) estimates of short ranged interactions combined with a Coulomb tail akin to the vacuum, we are able to confront successfully numerical and experimental estimates of the Fermi velocity renormalization. These results and their comparison with perturbation theory not only show the non-Fermi liquid character of graphene, but also prove the importance of lattice-scale physics for the quantitative description of the experimental data for the Fermi velocity renormalization in suspended graphene.