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

TL;DR

This paper investigates whether the newly observed X(4160) and X(3915) can be explained as charmonium states by analyzing their mass spectra and decay widths using quark models and the $^3P_0$ decay model.

Contribution

It provides a detailed analysis suggesting X(4160) is likely the charmonium state $ ext{η}_{c2}(2^1D_2)$, while X(3915) is unlikely to be $ ext{χ}_0(2^3P_0)$ based on decay width calculations.

Findings

X(4160) compatible with η_{c2}(2^1D_2) charmonium state

X(3915) unlikely to be χ_0(2^3P_0) due to decay width mismatch

Decay width calculations align with experimental data for X(4160) hypothesis

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 $\chi_0(3^3P_0), \chi_1(3^3P_1), \eta_{c2}(2^1D_2), \eta_c(4^1S_0)$ all can be candidates for the $X$(4160). However, only the decay width of the state $\eta_{c2}(2^1D_2)$ in our calculation is in good agreement with the data reported by Belle and the decay of $\eta_{c2}(2^1D_2)\to D\bar{D}$, which is not seen in experiment, is also forbidden. Therefore, it is reasonable to interpret the charmonium state $\eta_{c2}(2^1D_2)$ as the state X(4160). For the state X(3915), although the mass of $\chi_0(2^3P_0)$ 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 $\chi_0(2^3P_0)$ is disfavored in our calculation.