0000000000705859
AUTHOR
Chun-xu Yu
Observation of the first iso-spin Charmonium-like State $Z_c(4020)$ }
In this paper, we present a new experimental progress in brief on the recent observation of the charged charmonium-like state Z_c(4020)^{+/-} states and its iso-spin partner Z_c(4020)^{0} in pi pi hc process at the BESIII experiment. The charged Z_{c}(4020) is its decay into \pi^{+/-} hc final state, and carries electric charge, thus it contains at least four quarks. The observation of both charge and neutral state makes Z_{c}(4020) the first iso-spin triplet Z_{c} state observed in experiment.
Experimental review of e+e− →ππhcSupported by Joint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contracts No. U1332201, and National Natural Science Foundation of China (NSFC) under Contracts No. 11475207
We review the recent BESIII measurement of e+e− → ππhc in which its line shape is studied between the center-of-mass energies of 3.9 to 4.42 GeV and an iso-vector charmonium-like state Zc(4020) is observed in the invariant mass of πhc at the BESIII experiment. The charged Zc(4020)± is the second observed Zc state following Zc(3900), while the Zc(4020)0 is the first observed neutral Zc state. The line shape of σ(e+e− → ππhc) is also re-analyzed in view of searching for the Y state and the existence of the Y(4220) state is confirmed and compared with the previous work of the BESIII experiment.