A survey of heavy–heavy hadronic molecules

Xiang-Kun Dong,Feng-Kun Guo,Bing-Song Zou

Figure 1. The spectrum of hadronic molecules consisting of a pair of charmed mesons or baryons with I = 0 and P = +. The colored rectangle, green for a bound state and orange for a virtual state, covers the range of the pole position for a given system with the cutoff Λ varying in the range of [0.5, 1.0] GeV. Thresholds are marked by dotted horizontal lines. The rectangle closest to, but below, the threshold corresponds to the hadronic molecule in that system. In some cases, e.g. DD*, there are two rectangles for one system, with the upper edges exactly at the threshold. This corresponds to the situation that the pole moves from the second RS (left orange) to the first RS (right green) when Λ increases in the considered range. In some other cases where the pole positions of two systems overlap, small rectangles are used with the left (right) one for the system with the higher (lower) threshold.