1^{-+} light exotic mesons in QCD

Stéphan Narison (1)

1 LPTA - Laboratoire de Physique Théorique et Astroparticules

We systematically re-examine the extraction of the masses and couplings ofthe 1^{-+} hybrid, four-quark and molecule mesons from QCD spectral sum rules(QSSR). To NLO for the perturbative and power corrections, the hybrid mass isM_H=1.81(6) GeV and M_H < 2.2(2) GeV from the positivity of the spectralfunction. In the same way, but to LO, the four-quark state mass is M_{4q}=1.70(4) GeV and M_{4q} < 2.4(1) GeV, while the molecule mass is about 1.3(1)GeV. The observed \pi_1(1400) and \pi_1(1600) might be explained by atwo-component mixing with the set of input masses (1.2-1.3 ; 1.70-1.74) GeV andwith a mixing angle \theta= -(11.7+- 2.2)^0, which slightly favours amolecule/four-quark mixing, and which eventually suggests that the \pi_1(2015)is mostly an hybrid meson. Isospin and non-exotic partners of the previousstates and some of their radial excitations are also expected to be found inthe energy region around 2 GeV. Further tests of this phenomenological scenarioare required.

Domaines: Physique des Hautes Energies - Phénoménologie [hep-ph]

Stéphan Narison. 1^{-+} light exotic mesons in QCD. Physics Letters B, 2009, 675 (3-4), pp.319-325. ⟨10.1016/j.physletb.2009.04.012⟩. ⟨hal-00378180⟩