Logarithmic Corrections and Finite-Size Scaling in the Two-Dimensional   4-State Potts Model
  We analyze the scaling and finite-size-scaling behavior of the two-dimensional 4-state Potts model. We find new multiplicative logarithmic corrections for the susceptibility, in addition to the already known ones for the specific heat. We also find additive logarithmic corrections to scaling, some of which are universal. We have checked the theoretical predictions at criticality and off criticality by means of high-precision Monte Carlo data. 
Jes\'us Salas and Alan D. Sokal (NYU)