Speaker
Description
We explore the possibility to use ultra-peripheral proton-lead collisions at the LHC to study inclusive $J/\psi$ photoproduction, namely when a quasi-real photon emitted by the fully stripped lead ion breaks a proton to produce the $J/\psi$. Owing to the extremely large energies of the colliding hadrons circulating in the LHC, the range of accessible $W_{\gamma p}$ largely exceed what has been and will be studied at lepton-hadron colliders like HERA and the EIC. We obtain a leading-order inclusive-photoproduction cross section of order 50 $\mu$b, which we find large enough to be measured by CMS and LHCb. In addition, we find that inclusive-photoproduction can be isolated from possible hadroproduction processes by imposing the absence of significant activity in the lead-going direction, and may be further isolated by imposing rapidity-gap based cuts on detector activity. We estimate the background-to-signal ratio to be of order 0.001 and 0.01 at CMS and LHCb, respectively. In addition, we propose a method similar to the Jacquet-Blondel Method to reconstruct $W_{\gamma p}$ and the elasticity ($z$). Reconstructing these variables will allow kinematic regions to be defined that minimise theoretical uncertainty. We find that $z$ can be reconstructed with a resolution of 0.1, 0.15, and 0.2 in LHCb Pb$p$, CMS, and LHCb $p$Pb, respectively, where Pb$p$ and $p$Pb imply opposite beam directions.
