First measurement of near-threshold J/$ψ$ exclusive photoproduction off the proton
Creators: name: The GlueX Collaboration
name: Ali, A.
name: Amaryan, M.
name: Anassontzis, E. G.
name: Austregesilo, A.
name: Baalouch, M.
name: Barbosa, F.
name: Barlow, J.
name: Barnes, A.
name: Barriga, E.
name: Beattie, T. D.
name: Berdnikov, V. V.
name: Black, T.
name: Boeglin, W.
name: Boer, M.
name: Briscoe, W. J.
name: Britton, T.
name: Brooks, W. K.
name: Cannon, B. E.
name: Cao, N.
name: Chudakov, E.
name: Cole, S.
name: Cortes, O.
name: Crede, V.
name: Dalton, M. M.
name: Daniels, T.
name: Deur, A.
name: Dobbs, S.
name: Dolgolenko, A.
name: Dotel, R.
name: Dugger, M.
name: Dzhygadlo, R.
name: Egiyan, H.
name: Ernst, A.
name: Eugenio, P.
name: Fanelli, C.
name: Fegan, S.
name: Foda, A. M.
name: Foote, J.
name: Frye, J.
name: Furletov, S.
name: Gan, L.
name: Gasparian, A.
name: Gauzshtein, V.
name: Gevorgyan, N.
name: Gleason, C.
name: Goetzen, K.
name: Goncalves, A.
name: Goryachev, V. S.
name: Guo, L.
name: Hakobyan, H.
name: Hamdi, A.
name: Han, S.
name: Hardin, J.
name: Huber, G. M.
name: Hurley, A.
name: Ireland, D. G.
name: Ito, M. M.
name: Jarvis, N. S.
name: Jones, R. T.
name: Kakoyan, V.
name: Kalicy, G.
name: Kamel, M.
name: Kourkoumelis, C.
name: Kuleshov, S.
name: Kuznetsov, I.
name: Larin, I.
name: Lawrence, D.
name: Lersch, D. I.
name: Li, H.
name: Li, W.
name: Liu, B.
name: Livingston, K.
name: Lolos, G. J.
name: Lyubovitskij, V.
name: Mack, D.
name: Marukyan, H.
name: Matveev, V.
name: McCaughan, M.
name: McCracken, M.
name: McGinley, W.
name: McIntyre, J.
name: Meyer, C. A.
name: Miskimen, R.
name: Mitchell, R. E.
name: Mokaya, F.
name: Nerling, F.
name: Ng, L.
name: Ostrovidov, A. I.
name: Papandreou, Z.
name: Patsyuk, M.
name: Pauli, P.
name: Pedroni, R.
name: Pentchev, L.
name: Peters, K. J.
name: Phelps, W.
name: Pooser, E.
name: Qin, N.
name: Reinhold, J.
name: Ritchie, B. G.
name: Robison, L.
name: Romanov, D.
name: Romero, C.
name: Salgado, C.
name: Schertz, A. M.
name: Schumacher, R. A.
name: Schwiening, J.
name: Seth, K. K.
name: Shen, X.
name: Shepherd, M. R.
name: Smith, E. S.
name: Sober, D. I.
name: Somov, A.
name: Somov, S.
name: Soto, O.
name: Stevens, J. R.
name: Strakovsky, I. I.
name: Suresh, K.
name: Tarasov, V.
name: Taylor, S.
name: Teymurazyan, A.
name: Thiel, A.
name: Vasileiadis, G.
name: Werthmueller, D.
name: Whitlatch, T.
name: Wickramaarachchi, N.
name: Williams, M.
name: Xiao, T.
name: Yang, Y.
name: Zarling, J.
name: Zhang, Z.
name: Zhao, G.
name: Zhou, Q.
name: Zhou, X.
name: Zihlmann, B.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We report on the measurement of the $γp \rightarrow J/ψp$ cross section from $E_γ= 11.8$ 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 $dσ/dt$ 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 $\mathcal{B}(P_c^+ \rightarrow J/ψp)$ and cross sections $σ(γp \to P_c^+)\times\mathcal{B}(P_c^+ \to J/ψp) $.
description: 12 pages, 7 figures