Are the $X$(4160) and $X$(3915) charmonium states?

Abstract

Inspired by the newly observed $X$(4160) and $X$(3915) states, we analyze the mass spectrum of these states in different quark models and calculate their strong decay widths by the $^3P_0$ model. According to the mass spectrum of charmonium states predicted by the potential model, the states $χ_0(3^3P_0), χ_1(3^3P_1), η_{c2}(2^1D_2), η_c(4^1S_0)$ all can be candidates for the $X$(4160). However, only the decay width of the state $η_{c2}(2^1D_2)$ in our calculation is in good agreement with the data reported by Belle and the decay of $η_{c2}(2^1D_2)\to D\bar{D}$, which is not seen in experiment, is also forbidden. Therefore, it is reasonable to interpret the charmonium state $η_{c2}(2^1D_2)$ as the state X(4160). For the state X(3915), although the mass of $χ_0(2^3P_0)$ is compatible with the experimental value, the calculated strong decay width is much larger than experimental data. Hence, the assignment of X(3915) to charmonium state $χ_0(2^3P_0)$ is disfavored in our calculation.

9 pages, 8 figures