QCD vacuum is populated by instantons, corresponding to tunneling processes in the vacuum. This mechanism creates strong vacuum gluon fields. As result, QCD vacuum instantons induce very strong interactions between light quarks, which generate large dynamical light quark mass M for initially almost massless quarks and can bound these quarks to produce almost massless pions in accordance with the spontaneous breaking of chiral symmetry (SCSB). On the other hand, the QCD vacuum instantons also interact with heavy quarks and are responsible for the generation of the heavy-light quarks interactions, which have traces of the SCSB. As an example, we derive heavy quarks -- light mesons interaction terms for the light quark flavor number Nf=2 case. If we take the average instanton size rho=0.35 fm, and average inter-instanton distance R=0.856 fm from our previous estimates, we obtain at leading order in the 1/Nc expansion dynamical light quark mass M = 570 MeV and instanton media contribution to heavy quark mass Delta M=148 MeV. These factors define the coupling between heavy and light quarks and, certainly, between heavy quarks and light mesons.
