Origin of the approximate universality of distributions in equilibrium   correlated systems
  We propose an interpretation of previous experimental and numerical experiments, showing that for a large class of systems, distributions of global quantities are similar to a distribution originally obtained for the magnetization in the 2D-XY model . This approach, developed for the Ising model, is based on previous numerical observations. We obtain an effective action using a perturbative method, which successfully describes the order parameter fluctuations near the phase transition. This leads to a direct link between the D-dimensional Ising model and the XY model in the same dimension, which appears to be a generic feature of many equilibrium critical systems and which is at the heart of the above observations. 
Maxime Clusel (ILL, Phys-ENS), Jean-Yves Fortin (LPTH, LIFR-MI2P),   Peter C.W. Holdsworth (Phys-ENS)