About
We will describe a new measurement of coherent J/Psi photoproduction in LHC collisions with PbPb collisions at 5.02 TeV collected by CMS. In UPCs, the coherent heavy-flavor vector meson production via photon-nuclear interactions is of particular interest, as its cross section can directly probe the nuclear gluon density function. Since the two nuclei in symmetric UPCs can serve both as a photon-emitter projectile and a target, one has to disentangle contributions involving high- and low-energy photon-nucleus interactions to probe extremely small-x regimes. In this study, a new forward neutron tagging technique is utilized to solve this two-way ambiguity. We first review the technique of controlling the impact parameter of UPCs via forward neutron tagging established in the measurement of photon-photon QED processes. Then, we present the coherent J/psi photoproduction cross section as a function of photon-Pb center-of-mass energy in UPCs up to about a record energy of 400 GeV, corresponding to x ~ 5x10^{-5}. We discuss the physics implication of this new result, as well as opportunities in future LHC heavy ion runs.
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The talk
Credits and licence
- Institution
- CERN
- Department
- LHC Seminar
- Speaker
- Andre Govinda Stahl Leiton
- Year
- 2022
- Language
- English
- Source
- CERN
- Licence
- CERN, as CERN states it. CERN's terms
- Attribution
- © CERN. CERN provides its audiovisual media free of charge for educational and informational use, credited to CERN; this lecture is shown in CERN's own player.
- Who can watch
- CERN gives no rating. Invisible Network shows it to Teens profiles and older, judged from what the source says about it. How courses are placed