
Conference on "Variational and spectral methods in Quantum Field Theory"
Organizers: Volker Bach (Braunschweig), Maria J. Esteban (CNRS), Mathieu Lewin (CNRS), Eric Séré (ParisDauphine)
Marcello Porta (Zürich, Switzerland): "Manybody interactions in graphene"
Thursday 25 April 2013, 11:45  12:30
Amphi Hermite
In this talk I will discuss models for interacting fermions on the honeycomb lattice. The goal is to understand the low energy Physics of graphene, a newly discovered material which can be considered as the first realization of a (quasi) 2d crystal. I will discuss the effect of short range and electromagnetic interactions, using rigorous Renormalization Group methods. In the case of weak short range interactions (which are irrelevant in the Renormalization Group sense) I will present a theorem proving the universality of the conductivity, in the limit of zero temperature and zero frequency. In the case of unscreened electromagnetic interactions (which are marginal in the Renormalization Group sense) I will discuss a renormalized expansion for response and Schwinger functions; in general, anomalous (i.e. interaction dependent) exponents appear in the scaling of the correlations. In particular, from the expansion for the twopoint function we find that, in the infrared limit, the Fermi velocity flows to the speed of light while the quasiparticle weight tends to zero. In both cases, a crucial role is played by gauge symmetry and Ward identities. This is joint work with A. Giuliani and V. Mastropietro.