A 2+1 dimensional fermion field theory is proposed as a model for thelow-energy electronic excitations in monolayer graphene. The model consists ofN=2 four-component Dirac fermions moving in the plane and interacting via acontact interaction between charge densities. For strong couplings there is acontinuous transition to a Mott insulting phase. We present results of anextensive numerical study of the model's critical region, including the orderparameter, its associated susceptibility, and for the first time thequasiparticle propagator. The data enables an extraction of the criticalexponents at the transition, including the dynamical critical exponent, whichare hypothesised to be universal features of a quantum critical point. Therelation of our model with others in the literature is discussed, along withthe implications for physical graphene following from our value of the criticalcoupling.
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