The $J/\psi$-007 Experiment: A Search for the LHCb Charmed Pentaquarks in Hall C at Jefferson Lab

The Jefferson Lab experiment E12-16-007 ($J/\psi-007)$ ran in February 2019 and made a measurement of the elastic $J/\psi$ photo-production cross section as a function of proton momentum transfer variable $t$ and photon energy $E_{\gamma}$ in the region where all charm pentaquark states reported by the LHCb collaboration were discovered. The experiment has been performed using a bremsstrahlung beam generated by a 10.6 GeV incident electron beam traversing a copper radiator upstream of a hydrogen target in Hall C. The two high momentum spectrometers of Hall C, HMS and SHMS have been used to detect the $e^{+} e^{-}$ di-lepton $J/\psi$ decay pair in coincidence. In combination with the high incident photon flux, the optimized spectrometer settings provided the preferred kinematics where the s-channel resonant pentaquarks signals, if they exist, should strongly dominate over those of the regular $t$-channel $J/\psi$ production. We shall present results from the $J/\psi-007$ experiment and either confirm or refute the true resonant nature of these states.