New perspective on the scalar meson puzzle, from spontaneous chiral symmetry breaking beyond BCS

We introduce coupled channels of ladder Bethe-Salpeter mesons both in the bound state equation for mesons and in the mass gap equation for chiral symmetry. Consistency is insured by the Ward identities for axial currents, which preserve the Goldstone boson nature of the pion and prevent a systematic shift of the hadron spectrum. We study the decay of a scalar meson coupled to a pair of pseudoscalars. We also show that coupled channels reduce the breaking of chiral symmetry, with the same Feynman diagrams that appear in the coupling of a scalar meson to a pair of pseudoscalar mesons. Exact calculations are performed in a particular confining quark model, where we find that the ground state $I=0,$ ${}^3{P}_0\hspace{0.5em}q\overline{q}$ meson is the $f_0\mathrm{}\left(980\right)\mathrm{}$ with a partial decay width of 40 MeV. We also find a 30% reduction of the chiral condensate due to coupled channels.