First Measurement of Near-Threshold Exclusive Photoproduction off the Proton
We report on the measurement of the $$\gamma p \rightarrow J/\psi p$$ cross section from $$E_\gamma = 11.8$$ GeV down to the threshold at $8.2$ GeV using a tagged photon beam with the GlueX experiment. We find the total cross section falls toward the threshold less steeply than expected from two-gluon exchange models. The differential cross section $$d\sigma /dt$$ has an exponential slope of $$1.67 \pm 0.39$$ GeV$$^{-2}$$ at $10.7$ GeV average energy. The LHCb pentaquark candidates $$P_c^+$$ can be produced in the $$s$$-channel of this reaction. We see no evidence for them and set model-dependent upper limits on their branching fractions $$\mathcal{B}(P_c^+ \rightarrow J/\psi p)$$ and cross sections $$\sigma(\gamma p \to P_c^+)\times\mathcal{B}(P_c^+ \to J/\psi p) $$.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); George Washington Univ., Washington, DC (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP); National Science Foundation (NSF); German Research Foundation (DFG); Natural Sciences and Engineering Research Council of Canada (NSERC); Russian Foundation for Basic Research; UK Science and Technology Facilities Council; National Natural Science Foundation of China (NSFC)
- Contributing Organization:
- GlueX Collaboration
- Grant/Contract Number:
- AC05-06OR23177; SC0016583
- OSTI ID:
- 1574399
- Alternate ID(s):
- OSTI ID: 1557358; OSTI ID: 1594370
- Report Number(s):
- JLAB-PHY-19-2946; DOE/OR/23177-4686; arXiv:1905.10811; PRLTAO; TRN: US2100204
- Journal Information:
- Physical Review Letters, Vol. 123, Issue 7; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Strong decays of the latest LHCb pentaquark candidates in hadronic molecule pictures
|
journal | September 2019 |
Decays of P c into J / ψN and η c N with heavy quark spin symmetry
|
conference | August 2020 |
Strong decays of the latest LHCb pentaquark candidates in hadronic molecule pictures | text | January 2019 |
Similar Records
Plausibility of the LHCb in the GlueX total cross sections
Exclusive photoproduction of up to large values of Mandelstam variables and with CLAS