Speaker
Sean Dobbs
(Florida State University)
Description
Photoproduction of charmonium near threshold gives an excellent probe
for studying the gluonic structure of the nucleon. Of more recent
interest is the possibility of producing the $P_c^+$ pentaquark candidates
reported by LHCb in the s-channel reaction: $\gamma p -> P_c^+ \to p
J/\psi$. We report on the measurement of the total cross section
$\sigma(\gamma p \to p J/\psi)$ in 10 bins of photon beam energy down to the
threshold of $E_\gamma = 8.2$ GeV using a tagged photon beam with the
GlueX experiment at Jefferson Lab. We find the cross section as a
function of beam energy to fall less steeply near threshold than
expectations from lowest-order calculations. We also find no evidence
for the photoproduction of the Pc states and set upper limits on their
production and $\mathcal{B}(P_c^+ -> J/\psi p)$. We will also discuss the future
prospects for extending these measurements at GlueX.
Primary author
Sean Dobbs
(Florida State University)
