From Percolation to Logarithmic Conformal Field Theory

The smallest deformation of the minimal model M(2,3) that can accommodate Cardy's derivation of the percolation crossing probability is presented. It is shown that this leads to a consistent logarithmic conformal field theory at c=0. A simple recipe for computing the associated fusion rules is given. The differences between this theory and the other recently proposed c=0 logarithmic conformal field theories are underlined. The discussion also emphasises the existence of invariant logarithmic couplings that generalise Gurarie's anomaly number.