The BESIII collaboration recently reported the first observation of a new X(3872) production process e⁺e^-→ ωX(3872) in the energy region of 4.661-4.951 GeV. The result has been published in Physical Review Letters on April , 2023. [Phys. Rev. Lett. 130, 151904 (2023) ].

The experimentally observed quarkonium-like states beyond the conventional quarkonium spectrum are taken as the candidates of the exotic hadrons. As the first observed charmonium-like state, the famous X(3872) has been actively studied in the past decades. Its resonance parameters and quantum number are well measured, and multiple decays are observed in experiments. While how to interpret its nature is still a puzzle, and new experimental discovery is pivotal to understand its property. In addition to exploring the particle via its decays and resonance parameters, the production mechanisms transmit essential information about its internal structure.

Using 4.7fb^-1 of e⁺e^- collision data at center-of-mass energies from 4.661 to 4.951 GeV, searching for e⁺e^-→ωΧ(3872) is carried out at BESIII, where the X(3872) is reconstructed with the decay X(3872)→π⁺π^-J/ψ . We observe 24.6±5.3 signals with a significance of 7.8σ. This is the first observation of X(3872) in BESIII's e⁺e^- data from 4.661 to 4.951 GeV and the first observation of X(3872) in the production process e⁺e^-→ωΧ(3872). The Born cross section at each energy point is also reported. The line shape of the cross section indicates that the ωΧ(3872) signals may be from the decays of some nontrivial structure. This observation combined with its other mechanisms offers an additional window into the composition of the particle.

PRL Publication: https://doi.org/10.1103/PhysRevLett.130.151904

Inspire Entry: https://arxiv.org/abs/2212.07291