Configuration mixing in strange tetraquarks $Z_{cs}$

Abstract

The BESIII Collaboration has observed a candidate for a $c\bar{c}s\bar{u}$ tetraquark $Z_{cs}$ at $(3982.5_{-2.6}^{+1.8}\pm 2.1)$ MeV and width $(12.8_{-4.4}^{+5.3}\pm 3.0)$ MeV, while the LHCb Collaboration has observed a $Z_{cs}$ candidate in the $\jpsi K^-$ channel with mass of $(4003\pm 6_{-14}^{+4})$ MeV and width $(131\pm 15\pm 26)$ MeV. In this note we examine the possibility that these two states are distinct eigenstates of a mixing process similar to that which gives rise to two axial-vector mesons labeled by the Particle Data Group $K_1(1270)$ and $K_1(1400)$. The main point is that on top of a $\bar{c}c$ pair, the $Z_{cs}$ states have the same light quark content as the $K_1$-s. In the compact tetraquark picture this implies several additional states, analogous to members of the $K_1$ nonet. These states have not yet been observed, nor are they required in the molecular approach. Thus experimental discovery or exclusion of these extra states will be a critical test for competing models of exotic mesons with hidden charm.

6 pages, no figures. References added

References in corpus (10)

• Observation of new resonances decaying to $J/\psi K^{+}$ and $J/\psi \varphi$
• Observation of a near-threshold structure in the $K^{+}$ recoil-mass spectra in $e^{+}{e}^{-}\to K^{+}(D_s^{-}{D}^{\ast 0}+D_s^{\ast -}{D}^0)$
• Study of the lineshape of the ${\chi }_{c1}(3872)$ state
• Strange molecular partners of the $Z_c(3900)$ and $Z_c(4020)$
• Spectrum of the Hidden-Bottom and the Hidden-Charm/Strange Exotics in the Dynamical Diquark Model
• The strange partner of the $Z_c$ structures in a coupled-channels model
• Implications of the $Z_{cs}(3985)$ and $Z_{cs}(4000)$ as two different states
• Possibility of Narrow High-Mass Exotic States
• The new resonances Z_{cs}(3985) and Z_{cs}(4003) (almost) fill two tetraquark nonets of broken SU(3)_f
• Spectrum of Hidden-Charm, Open-Strange Exotics in the Dynamical Diquark Model

Cited by in corpus (12)

• An updated review of the new hadron states
• Chiral perturbation theory for heavy hadrons and chiral effective field theory for heavy hadronic molecules
• A combined analysis of the $Z_c(3900)$ and the $Z_{cs}(3985)$ exotic states
• Hidden-charm tetraquarks with strangeness in the chiral quark model
• Is $Z_{cs}(3982)$ a molecular partner of $Z_c(3900)$ and $Z_c(4020)$ states?
• Observation of a vector charmoniumlike state at 4.7 $\mathrm{GeV}/c^2$ and search for $Z_{cs}$ in $e^{+}{e}^{-}\to K^{+}{K}^{-}J/\psi$
• $Z_{cs}$ states from the $D_s^{\ast }{\bar{D}}^{\ast }$ and $J/\psi K^{\ast }$ coupled channels: Signal in $B^{+}\to J/\psi \varphi K^{+}$ decay
• $Z_{cs}(3985)$ in next-to-leading-order chiral effective field theory -- the first truncation uncertainty analysis
• Radiative decays of the heavy-quark-spin molecular partner of $T_{cc}^{+}$
• $X$ and $Z_{cs}$ in $B^{+}\to J/\psi \varphi K^{+}$ as $s$-wave threshold cusps and alternative spin-parity assignments to $X(4274)$ and $X(4500)$
• The $Z_{cs}$ states and the mixture of hadronic molecule and diquark-anti-diquark components within effective field theory
• Hunting for the heavy quark spin symmetry partner of $Z_{cs}$