On the percolation BCFT and the crossing probability of Watts Original Research Article

The logarithmic conformal field theory describing critical percolation is further explored using Wattsʹ determination of the probability that there exists a cluster connecting both horizontal and vertical edges. The boundary condition changing operator which governs Wattsʹ computation is identified with a primary field which does not fit naturally within the extended Kac table. Instead a “shifted” extended Kac table is shown to be relevant. Augmenting the previously known logarithmic theory based on Cardyʹs crossing probability by this field, a larger theory is obtained, in which new classes of indecomposable rank-2 modules are present. No rank-3 Jordan cells are yet observed. A highly non-trivial check of the identification of Wattsʹ field is that no Gurarie–Ludwig-type inconsistencies are observed in this augmentation. The article concludes with an extended discussion of various topics related to extending these results including projectivity, boundary sectors and inconsistency loopholes.