Analytic Bethe-Salpeter Description of the Lightest Pseudoscalar Mesons
  Within the Bethe-Salpeter formalism for instantaneous interactions, we describe, along a totally analytic route, the lightest pseudoscalar mesons by quark-antiquark bound states which show at least three indispensable general features, namely, the (almost) masslessness required for pions and kaons to be interpretable as (pseudo) Goldstone bosons, the suitable asymptotic behaviour in the limit of large spacelike relative momenta as determined by the relationship between quark mass function and Bethe-Salpeter amplitudes, and a pointwise behaviour for finite spacelike relative momenta suited for guaranteeing colour confinement. 
Wolfgang Lucha, Franz F. Sch\"oberl
hep-ph nucl-th