Radial excitations and exotic mesons via QCD sum rules

Mass spectrum of heavy quarkonium hybrids

“…This is in agreement with the results for the perturbative and gluon condensate contributions in Refs. [30][31][32]. It should be noted that both the expression for ρ GGG and that of ρ jj have a singularity at s = 4m 2 .…”

“…Another check is that our results for the perturbative and gluon condensate contributions are in numerical agreement with those in Refs. [30][31][32].…”

“…These hybrid correlation functions were originally studied in Refs. [30][31][32] in which the perturbative and gluon condensate contributions have been calculated to perform the QCD sum rule analysis. According to these calculations, the stability of the sum rules depends on the relative sign of the gluon condensate and the perturbative term.…”

“…In Refs. [30][31][32], Govaerts et al performed a QCD sum-rule analysis of the heavy quark hybrids including leading-order contributions up to the dimension four gluonic condensate. The sum rules of some J P C channels were unstable and thus these mass predictions were unreliable.…”

“…To date, there is some evidence of the exotic light hybrid with J P C = 1 −+ [25][26][27][28]. For heavy quarkonium hybrids, which hereafter we shall refer to as heavy quark hybrids, calculations including the constituent gluon model [29], the flux tube model [10], QCD sum rules [30][31][32][33][34][35][36] and lattice QCD [6,[37][38][39][40][41] have been performed. The hybrid supermultiplet structures described above were confirmed for the heavy quark sector in lattice QCD [6] and the P-wave quasigluon approach [42].…”