First Measurement of Near-Threshold J /ψ Exclusive Photoproduction off the Proton
Journal
Physical Review Letters
Date Issued
2019-08-13
Author(s) USM
Ali, A.
Amaryan, M.
Anassontzis, E. G.
Austregesilo, A.
Baalouch, M.
Barbosa, F.
Barlow, J.
Barnes, A.
Barriga, E.
Beattie, T. D.
Berdnikov, V. V.
Black, T.
Boeglin, W.
Boer, M.
Briscoe, W. J.
Britton, T.
Cannon, B. E.
Cao, N.
Chudakov, E.
Cole, S.
Cortes, O.
Crede, V.
Dalton, M. M.
Daniels, T.
Deur, A.
Dobbs, S.
Dolgolenko, A.
Dotel, R.
Dugger, M.
Dzhygadlo, R.
Egiyan, H.
Ernst, A.
Eugenio, P.
Fanelli, C.
Fegan, S.
Foda, A. M.
Foote, J.
Frye, J.
Furletov, S.
Gan, L.
Gasparian, A.
Gauzshtein, V.
Gevorgyan, N.
Gleason, C.
Goetzen, K.
Goncalves, A.
Goryachev, V. S.
Guo, L.
Hamdi, A.
Han, S.
Hardin, J.
Huber, G. M.
Hurley, A.
Ireland, D. G.
Ito, M. M.
Jarvis, N. S.
Jones, R. T.
Kakoyan, V.
Kalicy, G.
Kamel, M.
Kourkoumelis, C.
Kuznetsov, I.
Larin, I.
Lawrence, D.
Lersch, D. I.
Li, H.
Li, W.
Liu, B.
Livingston, K.
Lolos, G. J.
Lyubovitskij, V.
Mack, D.
Marukyan, H.
Matveev, V.
McCaughan, M.
McCracken, M.
McGinley, W.
McIntyre, J.
Meyer, C. A.
Miskimen, R.
Mitchell, R. E.
Mokaya, F.
Nerling, F.
Ng, L.
Ostrovidov, A. I.
Papandreou, Z.
Patsyuk, M.
Pauli, P.
Pedroni, R.
Pentchev, L.
Peters, K. J.
Phelps, W.
Pooser, E.
Qin, N.
Reinhold, J.
Ritchie, B. G.
Robison, L.
DOI
10.1103/PhysRevLett.123.072001
Abstract
We report on the measurement of the 𝛾𝑝→𝐽/𝜓𝑝 cross section from 𝐸𝛾=11.8 GeV down to the threshold at 8.2 GeV using a tagged photon beam with the GlueX experiment. We find that 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±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 ℬ(𝑃+ 𝑐→𝐽/𝜓𝑝) and cross sections 𝜎(𝛾𝑝→𝑃+ 𝑐)×ℬ(𝑃+ 𝑐→𝐽/𝜓𝑝).
Subjects
Política de Privacidad 
