  The QCD string breaking due to quark pair creation in the vacuum confining
field, possibly accompanied by vector, scalar or Nambu-Goldstone bosons, is
studied nonperturbatively. The scalar light pair creation vertex occurs due to
chiral symmetry breaking and has a confining form, which is computed explicitly
together with subleading vector contributions. Dependence on light quark mass
and flavor is specifically studied. The dominant scalar term is in good
agreement with the $^3P_0$ model and experimental data.
