Hunting for the heavy quark spin symmetry partner of Zcs

The discovery of a charged strange hidden-charm state Z(cs)(3985) implies another higher Z(cs)* state coupling to 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 (B) over bar 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(D) over bar *K and D-s2(D) over barK 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.

Automated summary

This paper discusses the charged strange hidden-charm state Z(cs)(3985) and another higher state Z(cs)*, as well as the possible hunt for Z(cs)* using experimental data. A hint for Z(cs)* in the (B) over bar J/psi K-K+ data at LHCb is pointed out, which is consistent with the production mechanism of the pentaquark P-c. The triangular singularity, which could enhance the production of Z(cs)* in electron-positron collision, is also studied. The production rate of Z(cs)* is predicted to be maximum at the e(+)e(-) center of mass energy of 4.648 GeV, lower than 4.681 GeV for Z(cs), due to the inverted coupling hierarchy. The bottom analogue under heavy quark flavor symmetry is also discussed.