Proposal for a CFT interpretation of Watts' differential equation for   percolation
  G. M. T. Watts derived that in two dimensional critical percolation the crossing probability Pi_hv satisfies a fifth order differential equation which includes another one of third order whose independent solutions describe the physically relevant quantities 1, Pi_h, Pi_hv.   We will show that this differential equation can be derived from a level three null vector condition of a rational c=-24 CFT and motivate how this solution may be fitted into known properties of percolation. 
Michael A.I. Flohr, Annekathrin Mueller-Lohmann