The methods of renormalized perturbation theory are used to find the critical exponents of the percolation and Yang-Lee edge singularity problems. Both of the above critical phenomena are described by ${\phi }^3$ field theories, and the Wilson functions are calculated explicitly in three dimensions to order three loops and summed using the Padé-Borel method. The resulting critical exponent values are consistent with direct series expansion results.

• Received 22 December 1981

DOI:https://doi.org/10.1103/PhysRevB.26.3923