Configuration Mixing In Strange Tetraquarks Z(Cs)

The BESIII Collaboration has observed a candidate for a c (c) over bars (u) over bar tetraquark Z(cs) at (3982.5+1.8 -2.6 +/- 2.1+ MeV and width (12.8(-4.4)(+5.3) +/- 3.0+ MeV, while the LHCb Collaboration has observed a Z(cs) candidate in the J=.K- channel with mass of (4003 +/- 6(-14)(+4) ) MeV and width (131 +/- 15 +/- 26) MeV. In this paper, 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 [P. Zyla et al., Prog. Theor. Exp. Phys. 6, 083C01 (2020)] K-1 (1270) and K-1 (1400). The main point is that on top of a (c) over barc 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.