Physics School Production and Decay of Pc States Dian-Yong Chen Southeast University 6th workshop on the XYZ particles 2020.01.20 Shang Outline 1. Short Review of Pc States 2. Decay of Pc States
3. Production of Pc States 4. Summary Physics School Short Review Episode I (LHCb 2015) Phys.Rev.Lett.115,072001(2015) @LHCb 1. Resonance parameters: Broad Narrow
2. JP assignments: one 3/2 and the other 5/2 with opposite parity 3. Relative branching fraction Pc(4380) Pc(4450) Physics School Short Review Possible interpretations-tetraquark QCD Sum Rule: H.X. Chen,E.L.Cui, et.al Eur.Phys.J.C76,572; Z.G.Wang Eur.Phys.J.C76,70; R Zhu, C. F. Qiao, Phys.Lett.B756,259
G. N. Li, X. G. He and M. He, JHEP1512,128 Quark Model C. Deng, J. Ping et.al, Phys.Rev.D95,014031 W. Park, A.Park, et.al, Phys.Rev.D95,054025 E. Santopinto and AlGiachina, Phys.Rev.D96,014014 Physics School Short Review Possible interpretations-Molecule Prediction before LHCb measurements J.J.Wu, R.Molina, E.Oset and B.S.Zhou,
Phys.Rev.Lett.105,232001; J.J.Wu, T.-S.H. Lee, and B.S.Zou, Phys.Rev.C85,044002 Z.C.Yang,Z.F.Sun,J.He,X.Loiu and S.L.Zhu, Chin.Phys.C36,6 W.L.Wang, F.Huang, Z.Y.Zhang and B.S.Zou, Phys.Rev.D84,015203 Further investigation after LHCb measurements QCD sum rule H.X.Chen, W.Chen, X.Liu et.al, Phys.Rev.Lett.115,172001 K.Azizi, Y.Sarac and H.Sundu, Phys.Rev.D95,014016 Potential model G.Yang and J. Ping, Phys.Rev.D95,014010
Physics School Short Review Possible interpretations- kinematics All or one of Pc States X.H.Liu,Q.Wang and Q.Zhao,Phys.Lett.B757,231 F.K.Guo,U.G.Meissner,W.Wang and Z.Yang, Phys.Rev.D92,071502 U.G.Meissner and J.A.Oller,Phys.Lett.B751,59 M.I.Eides, V.Y.Petrov and M.V.Polyakov, Phys.Rev.D93,054039
Physics School Short Review LHCb 2015 Episode II (LHCb 2019) LHCb 2019 Physics School Short Review Pc(4380)
Pc(4450) 2015 LHCb 2019 2019 Episode II (LHCb 2019) Pc(4380) Pc(4440) Pc(4457) 1. Resonance parameters:
2. Close to the thresholds of and Molecule nature of Pc Physics School Short Review (threshold) JP=(1/2)(1/2)(threshold) JP= (3/2)LHCb 2019 S-wave Molecular Picture Pc(4380) Pc(4440) Pc(4457) 1. Mass spectrum
H.X.Chen, W.Chen and S.L.Zhu, arXiv:1903,11001 R.Chen,Z.F.Sun,X.Liu and S.L.Zhu, arXiv:1903,11013; J.He, arXiv:1903.11872 M.Z.Liu,Y.W.Pan,F.Z.Peng et.al., arXiv:1903.11560 F.K.Guo,H.J.Ping, U.G.Meissner et.al, arXiv:1903.11503 Physics School Decay Effective interaction Physics School
Decay Coupling constants Coupling Constants depending on model parameter 1. Experimentally, ; 2. The coupling constants weakly depend on the model parameter; 3. In the same order for three Pc Phys.Rev.D100 (2019), 014022 states. 4. Similar parameter dependences
Physics School Decay observed channel- p Partial width depending on model parameter 1. Width Several MeV; 2. Large enough to be observed; 3. Consistent with molecular interpretation 4. Similar parameter dependences; 5. Ratios of the branching fractions very weakly model independent; close to 1; Similarity of Pc States?
Physics School Productions experimental measurements 3. Relative branching fraction Pc(438 0) Pc(445 0) 2015 2019
( ) ( / ) = ( / ) + . . ) % ( . .Pc(4312) + . .
. ( Pc(4440) . ) % + . . ) % ( . .Pc(4457) { Physics School Production Possible Mechanism
Quark Level (a): Vbu suppression; ccbar production suppressed (b): Suppressed due to color suppression in the hadronization (c): Supposed to be dominant Physics School Production Possible Mechanism Quark Level Transition amplitude Hadron Level
Physics School Production detail Weak interaction: Transition form factor for 1. No theoretical estimation ! 2. Similar to 3. Borrow these of but with a suppression Physics School
Production Results Branching fraction Phys.Rev. D100 (2019) 114002 1. Pc(4312)/Pc(4440): 104 Pc(4457): 10-5 2. Production ratio Physics School Production Results 1. Production ratio:
2. Decay Ratio Consistent with LHCb measurements ! Physics School Summary 1.Updated measurements: favor molecular interpretation 2. Decay: consistent with expectation 3. Production & Decay: Comparable with experimental data Physics School
Thank you for your attention ! Physics School
