Confinement- Deconfinement Phase Transition at nonzero Chemical Potential

We present arguments suggesting that large size overlapping instantons are the driving mechanism of the confinement-deconfinement phase transition at nonzero chemical potential $\mu$. The arguments are based on the picture that instantons at very large chemical potential in the weak coupling regime are localized configurations with finite size $\rho\sim\mu^{-1}$. At the same time, the same instantons at smaller chemical potential in the strong coupling regime are well represented by the so-called instanton-quarks with fractional topological charge $1/N_c$. We estimate the critical chemical potential $\mu_c(T)$ where this phase transition takes place as a function of temperature in the domain where our approach is justified. In this picture, the long standing problem of the ``accidental" coincidence of the chiral and deconfinement phase transitions at nonzero temperature (observed in lattice simulations) is naturally resolved. We also derive results at nonzero isospin chemical potential $\mu_I$ where direct lattice calculations are possible, and our predictions can be explicitly tested.