q\bar q$ Bound States in the Bethe-Salpeter Formalism
  We solve the Bethe-Salpeter equation in order to determine the spectrum of pseudoscalar and vector meson bound states for light as well as heavy quarks. The fermion propagators are obtained by solving the Schwinger-Dyson equation consistently with the Bethe-Salpeter equation, a procedure necessary for demonstrating the Goldstone nature of the pion in the chiral limit. Our results agree qualitatively and quantitatively with expectations both from current algebra for light quarks and from composite models for heavy quarks.} 
Pankaj Jain and Herman J. Munczek