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 transition between these two regimes takes place. We identify this
transition with confinement- deconfinement phase transition.
We also argue that the instanton quarks carry magnetic charges. As a
consequence of it, there is a relation between our picture and the standard
t'Hooft and Mandelstam picture of the confinement. We also comment on possible
relations of instanton-quarks with "periodic instantons", " center vortices",
and "fractional instantons" in the brane construction. We also argue that the
variation of the external parameter mu, which plays the role of the vacuum
expectation value of a "Higgs" field at mu >> \Lambda_{QCD}, allows to study
the transition from a "Higgs -like" gauge theory (weak coupling regime, mu>>
\Lambda_{QCD}) to ordinary QCD (strong coupling regime, mu<< \Lambda_{QCD}). We
also comment on some recent lattice results on topological charge density
distribution which support our picture.Comment: Invited talk delivered at the Light Cone Workshop, July 7-15, 2005,
Cairns, Australi