Radially excited states of η_c

In the framework of chiral quark model, the mass spectrum of η_c(ns) (n=1,…,6) is studied with Gaussian expansion method. With the wave functions obtained in the study of the mass spectrum, the open flavor two-body strong decay widths are calculated by using the ³P₀ model. The results show that the masses of η_c(1S) and η_c(2S) are consistent with the experimental data. The explanation of X(3940) as η_c(3S) is possible because the decay width of η_c(3S) is in the range of the experimental value of X(3940). Although the mass of X(4160) is about 110 MeV less than that of η_c(4S) and the decay width of X(4160) is much larger than that of η_c(4S), the assignment of X(4160) as η_c(4S) cannot be excluded due to the large uncertainty of the experimental decay width and the compatibility of the branching ratios of η_c(4S) with that of X(4160), and the mass of η_c(4S) can be shifted downwards by taking into account the coupling effect of the open charm channels. There are still no good candidates to η_c(5S) and η_c(6S)