Could the $X(3915)$ and the $X(3930)$ Be the Same Tensor State?

TL;DR

This study uses amplitude analysis of gamma-gamma to D Dbar and J/psi omega data to suggest that the X(3915) and X(3930) are the same tensor state with J^{PC}=2^{++}, challenging previous assumptions about its helicity dominance.

Contribution

It provides evidence that X(3915) and X(3930) are the same J^{PC}=2^{++} tensor state and highlights the significance of non-qar q components in its structure.

Findings

X(3915) is likely a J^{PC}=2^{++} state

X(3915) and X(3930) are the same resonance

Large helicity-0 contribution suggests non-qar q components

Abstract

By using a combined amplitude analysis of the $\gamma\gamma\rightarrow D\bar{D}$ and $\gamma\gamma\rightarrow J/\psi\omega$ data, we demonstrate that the $X(3915)$, which is quoted as a $J^{PC}=0^{++}$ state in the Particle Data Group table, is favored by the data to be a $J^{PC}=2^{++}$ state appearing in both channels, which means that the $X(3915)$ and the $X(3930)$ can be regarded as the same $J^{PC}=2^{++}$ state. Meanwhile, the data also prefer a large helicity-0 contribution of this tensor resonance to the amplitudes instead of the helicity-2 dominance assumed by {\it BABAR}, which may indicate a sizable portion of non-$q\bar q$ components in this state. Identifying the $X(3915)$ with the $X(3930)$ and abandoning the helicity-2 dominance for this tensor state are helpful for the further understandings of the properties of this state and also of the mysterious "$XYZ$" charmoniumlike resonances.