  We explore the structure of momentum distributions of Fermi liquids such as
completely polarized 3He, unpolarized liquid 3He, and nuclear matter at nonzero
temperatures. The study employs correlated density matrix theory and adapts the
algorithm to deal with spin- and isospin-dependent correlations. The analysis
is based on the factor decomposition of the one-body reduced density matrix.
The decomposition permits to distinguish between statistical correlations and
dynamic (direct) correlations. Together with the concept of renormalized
fermions the formal results open the pathway to investigate the thermal
boundaries of normal Fermi phases within correlated density matrix theory. We
also discuss possible transitions from normal phases to anomalous fermion
phases triggered by statistical correlations or by periodic phase-phase
structures.
