Comment on "${\eta }_c$ production in photon-induced interactions at the LHC"

Abstract

In "${\eta }_c$ production in photon-induced interactions at the LHC," \cite{Goncalves:2018yxc} Goncalves and Moreira discuss inclusive and exclusive ${\eta }_c$ production at $pp$ and $pA$ collisions at LHC energies. The exclusive channels are via two-photon and photon-Odderon interactions. This comment points out that there is a large additional source of almost-exclusive ${\eta }_c$ in ultra-peripheral collisions: from the radiative decay of $J/\psi$ that are produced in photon-nucleon interactions. Although the $J/\psi \to \gamma {\eta }_c$ branching ratio is small, the $J/\psi$ production cross-section is large enough that it dominates over the exclusive channels considered in \cite{Goncalves:2018yxc}, and is comparable to the non-exclusive production. In $J/\psi \to \gamma {\eta }_c$, the photon is very soft and therefore easy to miss, and the ${\eta }_c$ will have very similar kinematics to the $J/\psi$.

2 pages

References in corpus (2)

• ${\eta }_c$ production in photon - induced interactions at the LHC
• Two-Photon Interactions with Nuclear Breakup in Relativistic Heavy Ion Collisions

Cited by in corpus (8)

• Photonuclear and Two-photon Interactions at High-Energy Nuclear Colliders
• Exclusive ${\eta }_c$ production from small-$x$ evolved Odderon at a electron-ion collider
• ${\eta }_c$-nucleus bound states
• \boldmath{${\rm Y}$} and \boldmath{${\eta }_b$} mass shifts in nuclear matter
• Photon-Odderon interference in exclusive ${\chi }_c$ charmonium production at the Electron-Ion Collider
• Inclusive diffractive heavy quarkonium photoproduction in pp, pA and AA collisions
• Inclusive diffractive ${\eta }_{\mathrm{c}}$ production in pp, pA and AA modes at the LHC
• Ultra-peripheral-collision studies in the fixed-target mode with the proton and lead LHC beams