5. Theoretical Physics (CSN4)

Lattice Gauge Theory and Graphene

by Dr Alessandro Giuliani (Dipartimento di Matematica, Roma 3)

Aula Seminari (LNF)

Aula Seminari


Via Enrico Fermi, 40 00044 Frascati (Roma)
In this talk I introduce a lattice gauge theory model for graphene, which describes tight binding electrons hopping on the honeycomb lattice and interacting with a three-dimensional quantum U(1) gauge field. An exact RG analysis of the model leads to a renormalized expansion that is finite at all orders. The flow of the effective parameters is controlled thanks to exact lattice Ward Identities and a careful analysis of the discrete lattice symmetry properties of the model. The Fermi velocity increases up to the speed of light and Lorentz invariance spontaneously emerges in the infrared. The interaction produces critical exponents in the response functions: this removes the degeneracy present in the non interacting case and allows us to identify the dominant excitations. Finally, I discuss the effects of small fields coupled to local order parameters, as well as an anomalous gap equation for the masses, which suggests a possible mechanism for spontaneous mass generation at intermediate to strong coupling. Talk based on joint work with V. Mastropietro and M. Porta.