  We have developed a relativistic point-coupling model of nuclear many-body
dynamics constrained by the low-energy sector of QCD. The effective Lagrangian
is characterized by density-dependent coupling strengths determined by chiral
one- and two-pion exchange (with single and double delta isobar excitations)
and by large isoscalar background fields that arise through changes of the
quark condensate and the quark density at finite baryon density. The model has
been tested in the analysis of nuclear ground-state properties along different
isotope chains of medium and heavy nuclei. The agreement with experimental data
is comparable with purely phenomenological predictions. The built-in QCD
constraints and the explicit treatment of pion exchange restrict the freedom in
adjusting parameters and functional forms of density-dependent couplings. It is
shown that chiral pionic fluctuations play an important role for nuclear
binding and saturation mechanism, whereas background fields of about equal
magnitude and opposite sign generate the effective spin-orbit potential in
nuclei.
