5. Theoretical Physics (CSN4)

Universality and conformal invariance in non-solvable Ising models

by Dr Alessandro Giuliani (Univ. Roma Tre)

Aula Seminari (LNF)

Aula Seminari


Via Enrico Fermi, 40 00044 Frascati (Roma)
In this talk, I will introduce a class of non-solvable 2D Ising models with nearest neighbor plus weak finite range interactions, and present two recent rigorous results about the theory at the critical point (joint work with R. Greenblatt and V. Mastropietro): (1) Proof of the existence of the scaling limit for the multipoint energy correlations, as the lattice spacing goes to zero and the temperature goes to the critical one, with explicit bounds on the finite-mesh corrections. As expected, the limiting field theory defined by the set of the energy correlations coincides with the energy sector of the conformal field theory (CFT) with central charge c=1/2. (2) Proof that the finite size corrections to the free energy at criticality are universal, in the sense that they are exactly independent of the interaction. The corresponding central charge, defined in terms of the coefficient of the first subleading term to the free energy, as proposed by Affleck and Blote-Cardy-Nightingale, is constant and equal to 1/2, in agreement with the result on the energy correlations. In order to motivate these results, I will first review what is known or conjectured about the critical theory in the nearest neighbor 2D Ising model and in non-solvable versions of the same model. A digression about the CFT approach to the critical theory will be included.