A survey of heavy-heavy hadronic molecules

Abstract

The spectrum of hadronic molecules composed of heavy-antiheavy charmed hadrons has been obtained in our previous work. The potentials are constants at the leading order, which are estimated from resonance saturation. The experimental candidates of hadronic molecules, say X(3872), Y (4260), three Pc states and Pcs(4459), fit the spectrum well. The success in describing the pattern of heavy-antiheavy hadronic molecules stimulates us to give more predictions for the heavy-heavy cases, which are less discussed in literature than the heavy-antiheavy ones. Given that the heavyantiheavy hadronic molecules, several of which have strong experimental evidence, emerge from the dominant constant interaction from resonance saturation, we find that the existence of many heavyheavy hadronic molecules is natural. Among these predicted heavy-heavy states we highlight the DD * molecule and the D ( * ) Σ ( * ) c molecules, which are the partners of the famous X(3872) and Pc states. Quite recently, LHCb collaboration reported a doubly charmed tetraquark state, Tcc, which is in line with our results for the DD * molecule. With the first experimental signal of this new kind of exotic states, the upcoming update of the LHCb experiment as well as other experiments will provide more chances of observing the heavy-heavy hadronic molecules.

A new group of doubly charmed molecule with $T$-doublet charmed meson pair

“…Our numerical results show that the S -wave D 1 D 1 state with I(J P ) = 0(1 + ), the S -wave D 1 D * 2 states with I(J P ) = 0(1 + , 2 + , 3 + ), and the S -wave D * 2 D * 2 states with I(J P ) = 0(1 + , 3 + ) can be recommended as the prime doubly charmed molecular tetraquark candidates, which are consistent with the theoretical predictions in Ref. [14]. Meanwhile, the S -wave D 1 D 1 state with I(J P ) = 1(2 + ), the S -wave D 1 D * 2 state with I(J P ) = 1(3 + ), and the S -wave D * 2 D * 2 state with I(J P ) = 1(4 + ) may be the secondary doubly charmed molecular tetraquark candidates.…”

“…Y(4390) [69], Z + (4430) [70] H S [71][72][73] Z + (4248) [60], Z + (4430) [70] T T [50,74] S S [75] Doubly charmed systems HH [3-14] T + cc [1] HT [14,76] long-range interaction for the D D * state with I(J PC ) = 0(1 ++ ) is exactly same as the DD * state with I(J P ) = 0(1 + ) [7]. Inspired by the X(3872), a zoo of hidden-charm molecular tetraquark has been formed [40].…”

Prediction of new $T_{cc}$ states of $D^{*} D^{*}$ and $D^{*}_s D^{*}$ molecular nature

“…The D * D * system has been relatively unexplored. It is studied in [41] using meson exchange for the interaction and in [42] using the exchange of vector mesons guided by the local hidden gauge approach. Only the diagonal interaction and no decay channels are considered in [42], which aims at providing guidelines on possible states at the qualitative level.…”

“…It is studied in [41] using meson exchange for the interaction and in [42] using the exchange of vector mesons guided by the local hidden gauge approach. Only the diagonal interaction and no decay channels are considered in [42], which aims at providing guidelines on possible states at the qualitative level. The D * D * system in I = 0 and J = 1 + appears in [42] as a candidate for a bound state, and in [29,43] it also appears as a bound state using arguments of heavy quark spin symmetry and the data of [4].…”

“…Only the diagonal interaction and no decay channels are considered in [42], which aims at providing guidelines on possible states at the qualitative level. The D * D * system in I = 0 and J = 1 + appears in [42] as a candidate for a bound state, and in [29,43] it also appears as a bound state using arguments of heavy quark spin symmetry and the data of [4]. In [41] a state of D ( * ) D ( * ) nature, without distinguishing between D * D and D * D * , is also found to be a good candidate for a bound state in I = 0 and J P = 1 + .…”