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

Abstract

Abstract We report on some properties of the newly observed charged hidden-charmed open strange $$ Z_{cs}(3985)^- $$ Z cs ( 3985 ) - state by BESIII Collaboration. Assigning the quantum numbers $$ J^{P} = 1^{+}$$ J P = 1 + and the quark composition $$ c \bar{c} s\bar{u} $$ c c ¯ s u ¯ and considering it as the strange partner of the famous $$ Z_c(3900) $$ Z c ( 3900 ) state, we estimate the mass of the $$ Z_{cs}(3985)^- $$ 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, $$ Z_{bs}$$ Z bs , in the vacuum as well. For its mass we get $$ m_{Z_{bs}}= 10732^{+97}_{-46}~\hbox {MeV}$$ m Z bs = 10732 - 46 + 97 MeV , which may be checked via other nonperturbative approaches as well as future experiments. We present the dependence of the spectroscopic parameters of $$ Z_{cs}(3985)^- $$ Z cs ( 3985 ) - state on density and observe that these parameters are linearly changed with increasing in the density.