The newly observed $Z_{cs}(3985{)}^{-}$ state: in vacuum and a dense medium

Abstract

We report on some properties of the newly observed charged hidden-charmed open strange $Z_{cs}(3985{)}^{-}$ state by BESIII Collaboration. Assigning the quantum numbers $J^P=1^{+}$ and the quark composition $c\bar{c}s\bar{u}$ and considering it as the strange partner of the famous $Z_c(3900)$ state, we estimate the mass of the $Z_{cs}(3985{)}^{-}$ resonance in vacuum and compare it with the experimental data. We also investigate its mass, current coupling and vector-self energy in a medium with finite density. Our result on the mass in vacuum agrees well with the experimental data. We estimate the mass and current coupling of the b-partner of this state, $Z_{bs}$, in the vacuum as well. For its mass we get $ m_{Z_{bs}}= 10732^{+97}_{-46}~\mbox{MeV}$, which may be checked via other nonperturbative approaches as well as future experiments. We present the dependence of the spectroscopic parameters of $Z_{cs}(3985{)}^{-}$ state on density and observe that these parameters are linearly changed with increasing in the density.

11 Pages and 3 Figure