We use QCD sum rules to study the recently observed resonance-like structures in the π+ χc 1 mass distribution, Z1+ (4050) and Z2+ (4250), considered as D* + over(D, ̄)* 0 and D1+ over(D, ̄)0 + D+ over(D, ̄)10 molecules with the quantum number JP = 0+ and JP = 1-, respectively. We consider the contributions of condensates up to dimension eight and work at leading order in αs. We obtain mD* D* = (4.15 ± 0.12) GeV, around 100 MeV above the D* D* threshold, and mD1 D = (4.19 ± 0.22) GeV, around 100 MeV below the D1 D threshold. We conclude that the D* + over(D, ̄)* 0 state is probably a virtual state that is not related with the Z1+ (4050) resonance-like structure. In the case of the D1 D molecular state, considering the errors, its mass is consistent with both Z1+ (4050) and Z2+ (4250) resonance-like structures. Therefore, we conclude that no definite conclusion can be drawn for this state from the present analysis.
Bibliographical noteFunding Information:
This work has been partly supported by FAPESP and CNPq-Brazil and by the Korea Research Foundation KRF-2006-C00011.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics