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

Area of Science:

• High Energy Physics
• Particle Physics
• Quantum Chromodynamics

Background:

• The Particle Data Group classifies the X(3915) resonance as J(PC)=0(++).
• Previous analyses, such as by BABAR, assumed helicity-2 dominance for tensor resonances.
• Understanding charmoniumlike resonances is crucial for advancing beyond the Standard Model.

Purpose of the Study:

• To re-evaluate the quantum numbers of the X(3915) resonance.
• To investigate the nature of charmoniumlike states, including the X(3915) and X(3930).
• To explore the composition of tensor resonances and their production mechanisms.

Main Methods:

• Combined amplitude analysis of experimental data from γγ→DD̅ and γγ→J/ψω processes.
• Investigating different spin-parity assignments for the X(3915) resonance.
• Analyzing the helicity contributions to the resonance amplitudes.

Main Results:

• The data strongly favor the X(3915) being a J(PC)=2(++) state, not J(PC)=0(++).
• The X(3915) and X(3930) resonances are likely the same J(PC)=2(++) state.
• A significant helicity-0 contribution is preferred over helicity-2 dominance for this tensor resonance.

Conclusions:

• The X(3915) resonance's properties are reinterpreted as J(PC)=2(++), suggesting it is identical to the X(3930).
• The dominance of helicity-0 contribution implies potential non-qq̅ components in this tensor state.
• These findings offer new insights into charmoniumlike resonances and their underlying physics.