  A financial market is a system resulting from the complex interaction between
participants in a closed economy. We propose a minimal microscopic model of the
financial market economy based on the real economy's symmetry constraint and
minimality requirement. We solve the proposed model analytically in the
mean-field regime, which shows that various kinds of universal power-law-like
behaviors in the financial market may depend on one another, just like the
critical exponents in physics. We then discuss the parameters in the proposed
model, and we show that each parameter in our model can be related to
measurable quantities in the real market, which enables us to discuss the cause
of a few kinds of social and economic phenomena.
