Zipf's Law and the Universality Class of the Fragmentation Phase   Transition
  We show that Zipf's Law for the largest clusters is not valid in an exact sense at the critical point of the fragmentation phase transition, contrary to previous claims. Instead, the extracted distributions of the largest clusters reflects the choice of universality class through the value of the critical exponent tau. 
Wolfgang Bauer, Scott Pratt and Brandon Alleman