Two topics on charmonium-like states

Two topics about the charmonium-like spectrum are discussed here. In the first part, we present that in a combined analysis of γγ→DD‾, J/ψω processes the X(3915) is preferred to be the same tensor state as the X(3930) by the experiment data. In the second part, we show that, in a coupled-channel unitarized model, the mass distribution data sets of X(4260)→J/ψπ+π−, (DD⁎)±π∓, (D⁎D⁎)±π∓ could be described perfectly at the same time. By analyzing the singularity structure of the amplitudes, one could find that the peak of Zc(3900) line-shape is mainly contributed by a thirdsheet pole at about 3.875 ± 0.016GeV. The analysis clearly demonstrates that a good quantitative description of the mass distribution data requires the pole contribution to the Zc(3900) line-shape rather than the pure cusp effect.