Operator product expansion and non-perturbative renormalization
  It has been recently proposed to use the operator product expansion to evaluate the expectation values of renormalized operators without the need of a direct computation of the relevant renormalization constants. We test the viability of this idea in the two-dimensional non-linear sigma-model discussing the non-perturbative renormalization of the energy-momentum tensor. 
Sergio Caracciolo, Andrea Montanari and Andrea Pelissetto