We present an exact method based on a hyperspherical harmonic expansion to study systems made of quarks and antiquarks of the same flavor. Our formalism reproduces and improves the results obtained with variational approaches. This analysis shows that identical-flavor four-quark systems with non-exotic 2+ + quantum numbers may be bound independently of the quark mass. 0+ - and 1+ - states become attractive only for larger quarks masses.
Bibliographical noteFunding Information:
This work has been partially funded by MCyT under Contract No. FPA2004-05616, by JCyL under Contract No. SA104/04, and by GV under Contract No. GV05/276.