Abstract
The nature of the recently discovered Z_cZc and Z_bZb structures is intriguing. Their charge forces its minimal quark content to be Q\bar Q q\bar qQQ‾qq‾ (where Q=\{c,b\}Q={c,b} and q=\{u,d\}q={u,d}). In this work we perform a molecular coupled-channels calculation of the I^G(J^{PC})=1^+(1^{+-})IG(JPC)=1+(1+−) charm and bottom sectors in the framework of a constituent quark model which satisfactorily describes a wide range of properties of (non-)conventional hadrons containing heavy quarks. All the relevant channels are included for each sector, i.e.: The D^{(\ast)}\bar D^{\ast}+h.c.D(*)D‾*+h.c., \pi J/\psiπJ/ψ and \rho\eta_cρηc channels for the Z_cZc and B^{(\ast)}B^{\ast}B(*)B* and \Upsilon(nS)\piΥ(nS)π (n=1,2,3n=1,2,3) channels for the Z_bZb analysis. Possible structures of these resonances will be discussed.
Highlights
The search of exotic structures in the heavy meson spectra, beyond the simplest qqstructure, is relatively recent
The Zc(4020) resonance, close to the D∗ D ∗ threshold, was discovered soon after at BESIII in the e+e− → π+π−hc channel with a mass of M = (4022.9 ± 0.8 ± 2.7) MeV/c2 and a width of Γ = (7.9 ± 2.7 ± 2.6) MeV [9]
In this work we explore the I G(J PC ) = 1+(1+−) charm and bottom sector in a coupledchannels scheme, including the closest meson-meson thresholds
Summary
The search of exotic structures in the heavy meson spectra, beyond the simplest qqstructure, is relatively recent. The so-called Zb(10610) and Zb(10650) where charged structures close to the BB∗ and B∗B∗ thresholds, respectively, spotted in the Υ (5S) → π+π−Υ (nS) reaction. Few years later, their charmonium partners arrived. The BESIII and Belle Collaborations discovered the Zc(3900) [6, 7], close to the DD ∗ threshold, in the π+π−J /ψ invariant mass spectrum of the e+e− → π+π−J /ψ process at s = 4.26 GeV. The Zc(4020) resonance, close to the D∗ D ∗ threshold, was discovered soon after at BESIII in the e+e− → π+π−hc channel with a mass of M = (4022.9 ± 0.8 ± 2.7) MeV/c2 and a width of Γ = (7.9 ± 2.7 ± 2.6) MeV [9]
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