Mixing of scalar tetraquark and quarkonia states in a chiral approach

A chiral invariant Lagrangian describing the tetraquark-quarkonia interaction is considered at the leading and subleading order in the large-$N_c$ expansion. Spontaneous chiral symmetry breaking generates mixing of scalar tetraquark and quarkonia states and nonvanishing tetraquark condensates. In particular, the mixing strength is related to the decay strengths of tetraquark states into pseudoscalar mesons. The results show that scalar states below 1 GeV are mainly four-quark states and the scalars between 1 and 2 GeV quark-antiquark states, probably mixed with the scalar glueball in the isoscalar sector.