Locations of multicritical points for spin glasses on regular lattices

We present an analysis leading to precise locations of the multicritical points for spin glasses on regular lattices. The conventional technique for determination of the location of the multicritical point was previously derived using a hypothesis emerging from duality and the replica method. In the present study, we propose a systematic technique, by an improved technique, giving more precise locations of the multicritical points on the square, triangular, and hexagonal lattices by carefully examining the relationship between two partition functions related with each other by the duality. We can find that the multicritical points of the +/-J Ising model are located at pc=0. 890813 on the square lattice, where pc means the probability of Jij=J (>0), at pc=0. 835985 on the triangular lattice, and at pc=0. 932593 on the hexagonal lattice. These results are in excellent agreement with recent numerical estimations.