Hybrid mesons with auxiliary fields

Abstract

Hybrid mesons are exotic mesons in which the color field is not in the ground state. Their understanding deserves interest from a theoretical point of view, because it is intimately related to nonperturbative aspects of QCD. Moreover, it seems that some recently detected particles, such as the π 1 (1600) and the Y (4260), are serious hybrid candidates. In this work, we investigate the description of such exotic hadrons by applying the auxiliary fields technique (also known as the einbein field method) to the widely used spinless Salpeter Hamiltonian with appropriate linear confinement. Instead of the usual numerical resolution, this technique allows to find simplified analytical mass spectra and wave functions of the Hamiltonian, which still lead to reliable qualitative predictions. We analyse and compare two different descriptions of hybrid mesons, namely a two-body qq system with an excited flux tube, or a three-body qqg system. We also compute the masses of the 1 −+ hybrids. Our results are shown to be in satisfactory agreement with lattice QCD and other effective models.

Analysis on heavy quarkonia transitions with pion emission in terms of the QCD multipole expansion and determination of mass spectra of hybrids

“…Yan and Kuang used the phenomenological potential given by Buchmüller and Tye [7] to evaluate the mass of the ground state of hybrid, instead, in our work, we take some effective potential models which are based on the color-flux-tube model. All the details about the definitions and notations can be easily found in literature [11,12,13,17,18,19].…”

Nature ofX(4260)

“…Because of the situation as described above many theoretical papers have been devoted to the investigation on X(4260). In the literature, many models have been made, e.g., χ c0 ρ 0 molecule [8], ωχ c1 molecule [9], ccg hybrid state [10][11][12][13][14], Λ cΛc bayronium [15], D 1D or D 0D which hints that the X(4260) may have a large coupling to ωχ c0 -though it is not totally clear whether the ωχ c0 is from the continuum spectrum or the X(4260) resonance, or from both. Furthermore, the cross section of h c ππ channel [35] is also measured at this energy implying that the X(4260) may also couple to it.…”

Coulomb gauge approach to qq̄g hybrid mesons

“…Theoretically, the structure of the π 1 states remains unclear. They could be hybrid or tetraquark mesons with most theoretical studies [13,14] investigating the former. Lattice gauge simulations [15,16,17,18,19] predict the lightest hybrid meson is between 1.7 and 2.1 GeV and results from the Flux Tube model [20,21,22] also span much of this range.…”