> nucl-ex > arXiv:1905.10811
Nuclear Experiment
arXiv:1905.10811 (nucl-ex)
[Submitted on 26 May 2019 (v1), last revised 10 Sep 2019 (this version, v2)]
Title:First measurement of near-threshold J/$ψ$ exclusive photoproduction off the proton
Authors:The GlueX Collaboration: A. Ali, M. Amaryan, E. G. Anassontzis, A. Austregesilo, M. Baalouch, F. Barbosa, J. Barlow, A. Barnes, E. Barriga, T. D. Beattie, V. V. Berdnikov, T. Black, W. Boeglin, M. Boer, W. J. Briscoe, T. Britton, W. K. Brooks, B. E. Cannon, N. Cao, E. Chudakov, S. Cole, O. Cortes, V. Crede, M. M. Dalton, T. Daniels, A. Deur, S. Dobbs, A. Dolgolenko, R. Dotel, M. Dugger, R. Dzhygadlo, H. Egiyan, A. Ernst, P. Eugenio, C. Fanelli, S. Fegan, A. M. Foda, J. Foote, J. Frye, S. Furletov, L. Gan, A. Gasparian, V. Gauzshtein, N. Gevorgyan, C. Gleason, K. Goetzen, A. Goncalves, V. S. Goryachev, L. Guo, H. Hakobyan, A. Hamdi, S. Han, J. Hardin, G. M. Huber, A. Hurley, D. G. Ireland, M. M. Ito, N. S. Jarvis, R. T. Jones, V. Kakoyan, G. Kalicy, M. Kamel, C. Kourkoumelis, S. Kuleshov, I. Kuznetsov, I. Larin, D. Lawrence, D. I. Lersch, H. Li, W. Li, B. Liu, K. Livingston, G. J. Lolos, V. Lyubovitskij, D. Mack, H. Marukyan, V. Matveev, M. McCaughan, M. McCracken, W. McGinley, J. McIntyre, C. A. Meyer, R. Miskimen, R. E. Mitchell, F. Mokaya, F. Nerling, L. Ng, A. I. Ostrovidov, Z. Papandreou, M. Patsyuk, P. Pauli, R. Pedroni, L. Pentchev, K. J. Peters, W. Phelps, E. Pooser, N. Qin, J. Reinhold, B. G. Ritchie
, L. Robison, D. Romanov, C. Romero, C. Salgado, A. M. Schertz, R. A. Schumacher, J. Schwiening, K. K. Seth, X. Shen, M. R. Shepherd, E. S. Smith, D. I. Sober, A. Somov, S. Somov, O. Soto, J. R. Stevens, I. I. Strakovsky, K. Suresh, V. Tarasov, S. Taylor, A. Teymurazyan, A. Thiel, G. Vasileiadis, D. Werthmueller, T. Whitlatch, N. Wickramaarachchi, M. Williams, T. Xiao, Y. Yang, J. Zarling, Z. Zhang, G. Zhao, Q. Zhou, X. Zhou, B. Zihlmann
et al. (35 additional authors not shown)
Abstract: 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) $.
Subjects: Nuclear Experiment (nucl-ex)
Cite as: arXiv:1905.10811 [nucl-ex]
(or arXiv:1905.10811v2 [nucl-ex] for this version)
Journal reference: Phys. Rev. Lett. 123, 072001 (2019)
Related DOI: https://doi.org/10.1103/PhysRevLett.123.072001
DOI(s) linking to related resources
From: Lubomir Pentchev [view email]
[v1] Sun, 26 May 2019 14:59:49 UTC (79 KB)
[v2] Tue, 10 Sep 2019 20:25:40 UTC (158 KB)
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