Observation of e+e− → χc1 at BESIII.

In electron-positron annihilations, the process of e+e− → χc1 can occur via the production of two virtual photons or through neutral current, therefore being suppressed with respect to the normal annihilation process via one virtual photon. Using a dedicated scan sample around the χc1 mass, the direct production of χc1 has been established for the first time in experiments. This provides a new approach for the study of the internal nature of hadrons. [ABSTRACT FROM AUTHOR]