@article{7a5d427e61a043759b6a8f2015bc2d8f,
title = "First Measurement of Near-Threshold J /ψ Exclusive Photoproduction off the Proton",
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 Pc+ 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(Pc+→J/ψp) and cross sections σ(γp→Pc+)×B(Pc+→J/ψp).",
author = "{GlueX Collaboration} and A. Ali and M. Amaryan and Anassontzis, {E. G.} and A. Austregesilo and M. Baalouch and F. Barbosa and J. Barlow and A. Barnes and E. Barriga and Beattie, {T. D.} and Berdnikov, {V. V.} and T. Black and W. Boeglin and M. Boer and Briscoe, {W. J.} and T. Britton and Brooks, {W. K.} and Cannon, {B. E.} and N. Cao and E. Chudakov and S. Cole and O. Cortes and V. Crede and Dalton, {M. M.} and T. Daniels and A. Deur and S. Dobbs and A. Dolgolenko and R. Dotel and M. Dugger and R. Dzhygadlo and H. Egiyan and A. Ernst and P. Eugenio and C. Fanelli and S. Fegan and Foda, {A. M.} and J. Foote and J. Frye and S. Furletov and L. Gan and A. Gasparian and V. Gauzshtein and N. Gevorgyan and C. Gleason and K. Goetzen and A. Goncalves and Goryachev, {V. S.} and L. Guo and Ritchie, {B. G.}",
note = "Publisher Copyright: {\textcopyright} 2019 American Physical Society.",
year = "2019",
month = aug,
day = "13",
doi = "10.1103/PhysRevLett.123.072001",
language = "English (US)",
volume = "123",
journal = "Physical Review Letters",
issn = "0031-9007",
publisher = "American Physical Society",
number = "7",
}