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

Abstract

By using a combined amplitude analysis of the $\gamma \gamma \to D\bar{D}$ and $\gamma \gamma \to J/\psi \omega$ 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.

5 pages, 1 table, 3 figures, version accepted for publication in Phys. Rev. Lett.; Title changed, significantly improved discussions, minor corrections to formulas and figures, main framework and results not changed

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• Heavy quarkonium: progress, puzzles, and opportunities
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• Comprehensive Amplitude Analysis of $\gamma \gamma \to {\pi }^{+}{\pi }^{-},{\pi }^0{\pi }^0$ and $\overline{K}K$ below 1.5 GeV
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Cited by in corpus (9)

• Pentaquark and Tetraquark states
• Charmonium spectrum and their electromagnetic transitions with higher multipole contributions
• Charmonium resonances in the 3.9 GeV/$c^2$ energy region and the $X(3915)/X(3930)$ puzzle
• The Dynamical Diquark Model: First Numerical Results
• Quarkonium $h$ States As Arbiters of Exoticity
• Search for $X(3872)$ and $X(3915)$ decay into ${\chi }_{c1}{\pi }^0$ in $B$ decays at Belle
• On the nature of X(3960)
• Shedding light on the $X(3930)$ and $X(3960)$ states with the $B^{-}\to K^{-}J/\psi \omega$ reaction
• Comment on the X(3915) nonstandard hadron candidate