Quark Matter 2023

Session

UPC

6 Sept 2023, 08:30

Hilton of the Americas, 1600 Lamar, Houston, Texas, 77010, USA

Conveners

UPC: (1)

• Daniel Tapia Takaki (University of Kansas)

609. Probing small-$x$ nuclear gluonic structure via coherent charmonium photoproduction in ultraperipheral PbPb collisions at CMS

Jiazhao Lin (Rice University (US))

06/09/2023, 08:30

UPC Physics

Oral

Gluons are found to become increasingly dominant constituents of nuclear matter when being probed at higher energies or smaller Bjorken-$x$ values. This has led to the question of the ultimate fate of nuclear gluonic structure at extreme density. In ultraperipheral collisions (UPCs) of relativistic heavy ions, the coherent heavy-flavor vector meson production via photon-nuclear interactions is...

302. Exclusive $J/\psi$ Photoproduction and Entanglement-Enabled Spin Interference in Ultra-Peripheral Collisions at STAR

Ashik Ikbal Sheikh

06/09/2023, 08:50

UPC Physics

Oral

In ultra-peripheral collisions (UPCs), exclusive vector meson photoproduction, e.g., $\rho^{0}$ and $J/\psi$, has been considered one of the most sensitive probes to the gluon structure in heavy nuclei. Recently, it was discovered that the linear polarization of the photons involved in these processes can enable measurements of the nuclear geometry through the so-called entanglement-enabled...

170. First global study of super dense gluonic matter with UPCs by ALICE

Simone Ragoni (Creighton University (US))

06/09/2023, 09:10

UPC Physics

Oral

ALICE has been the first experimental collaboration observing a moderate nuclear suppression down to low Bjorken x in lead nuclei using coherent J/$\psi$ photoproduction. In this talk, we present new results extending the studies of the photonuclear cross section by covering the Bjorken-x interval of $1.1 \cdot 10^{-5} < x < 3.3 \cdot 10^{-2}$, corresponding to the photon-nuclear energies $17...

585. Looking for QGP signatures in ultraperipheral PbPb collisions

Sruthy Jyothi Das (University of Colorado Boulder (US))

06/09/2023, 09:30

UPC Physics

Oral

Ultraperipheral collisions of relativistic heavy ion beams lead to a diverse set of photon-nucleus (photonuclear) interactions. The measurements of particle production in photonuclear reactions can shed light on the QCD dynamics of the novel, extremely asymmetric colliding systems, with energies between those available at RHIC and the LHC. Previous studies by ATLAS indicate significant...

384. Quarkonia production in ultra-peripheral PbPb collisions at LHCb

Xiaolin Wang (South China Normal University (CN))

06/09/2023, 09:50

UPC Physics

Oral

Measurements of quarkonia production in peripheral and ultra-peripheral
heavy-ion collisions are sensitive to photon-photon and photon-nucleus interac-
tions, the partonic structure of nuclei, and to the mechanisms of vector-meson
production. LHCb has studied production of the J/ψ and ψ(2S) charmonium
states in peripheral and ultra-peripheral collisions using PbPb data at...

420. Illuminating the impact-parameter dependence of UPC dijet photoproduction

Petja Paakkinen

06/09/2023, 10:10

UPC Physics

Oral

In this talk, we present new NLO pQCD predictions for photoproduction of dijets in UPC PbPb collisions at 5.02 TeV with realistic photon flux and up-to-date nuclear parton distribution functions (nPDFs). We calculate nuclear form factor for the impact parameter-dependent flux using Woods-Saxon density profile and compare the result to a widely-used point-like approximation. We show that a...