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Title: First Measurement of Near-Threshold J / ψ Exclusive Photoproduction off the Proton

Journal Article · · Physical Review Letters
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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
Citation Metrics:
Cited by: 99 works
Citation information provided by
Web of Science

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Cited By (3)

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


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