Light 1-+ exotics: molecular resonances

Understand

Highlights in the search for nonconventional (non qqbar) meson states are the pi_1(1400) and pi_1(1600) exotic candidates.

• Should they exist, mounting theoretical arguments suggest that they are tetraquark molecular resonances excitable by meson rescattering.
• We report a new tetraquark calculation within a model field theory approximation to Quantum Chromodynamics in the Coulomb gauge supporting this conjecture.
• We also strengthen this claim by consistently contrasting results with exotic state predictions for hybrid (q qbar g) mesons within the same theoretical framework.