  Statistical mechanics has proven to be able to capture the fundamental rules
underlying phenomena of social aggregation and opinion dynamics, well studied
in disciplines like sociology and psychology. This approach is based on the
underlying paradigm that the interesting dynamics of multi-agent systems emerge
from the correct definition of few parameters governing the evolution of each
individual. Into this context, we propose a particular model of opinion
dynamics based on the psychological construct named "cognitive dissonance". Our
system is made of interacting individuals, the agents, each bearing only two
dynamical variables (respectively "opinion" and "affinity") self-consistently
adjusted during time evolution. We also define two special classes of
interacting entities, both acting for a peace mediation process but via
different course of action: "diplomats" and "auctoritates". The behavior of the
system with and without peace mediators (PMs) is investigated and discussed
with reference to corresponding psychological and social implications.
