Abstract
The discovery of a charged strange hidden-charm state Z_{cs}(3985) implies another higher Z^*_{cs} state coupling to {bar{D}}_s^{*-}D^{*0} + c.c under the heavy quark spin symmetry. In this paper we discuss a possible hunt for it with data taken at existing facilities. We point out a hint for Z^*_{cs} in the data of {bar{B}}_s^0 rightarrow J/psi K^- K^+ at LHCb, though weak, in line with the production mechanism of pentaquark P_c. We also study the triangular singularity which would possibly enhance the production of Z^*_{cs} in electron-positron collision. Surprisingly, the production rate of Z^*_{cs} is expected to be maximum at the e^+ e^- center of mass energy of 4.648 GeV, which is lower than 4.681 GeV for Z_{cs} due to the inverted coupling hierarchy of D_{s1}{bar{D}}^* K and D_{s2}{bar{D}}K in the triangle diagrams. Their bottom analogue under heavy quark flavor symmetry is also discussed. Our theoretical analysis would confront with future experiment of LHCb, BESIII, and Bell II.
Highlights
The evidence of strange pentaquark Pcs(4459) from LHCb Collaboration [1], though only 3σ significance, marked the dawn of strange era for the exploration of exotic candidates
It is close to the Ds− D∗0 and Ds∗− D0 thresholds with the probable quantum number being J P = 1+
This motivates its interpretation of Ds− D∗0 + Ds∗− D0 molecular state as the strange partner of Zc(3900) in various scenarios, e.g. in QCD sum rules before [3,4] and after its observation [5,6,7,8,9,10,11,12]
Summary
The evidence of strange pentaquark Pcs(4459) from LHCb Collaboration [1], though only 3σ significance, marked the dawn of strange era for the exploration of exotic candidates. The production rate of Zc∗s is expected to be maximum at the e+e− center of mass energy of 4.648 GeV, which is lower than 4.681 GeV for Zcs due to the inverted coupling hierarchy of Ds1 D ∗ K and Ds2 D K in the triangle diagrams. If considering them as two different states, the Zcs(3985) → J/ψ K decay is suppressed in the limit of the HQSS [47], and the Zcs(4220) at LHCb would be the expected axial-vector Ds∗ D ∗ molecular.
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