Quark Matter 2025

Session

Parallel session 15

8 Apr 2025, 08:40

Goethe University Frankfurt, Campus Westend, Theodor-W.-Adorno-Platz 1, 60629 Frankfurt am Main, Germany

Conveners

Parallel session 15: Physics of ultraperipheral collisions I

• Andre Govinda Stahl (CERN)

520. New probes of nuclear gluon dynamics through photoproduction of charm in inelastic ultra-peripheral Pb–Pb collisions with ALICE

Sigurd Nese (University of Oslo (NO))

08/04/2025, 08:40

Physics of ultraperipheral collisions

Oral

In an ultra-peripheral collision, where the impact parameter is larger than the sum of the nuclear radii, the nuclei mainly interact electromagnetically. These reactions are mediated by virtual photons. A photon can interact with a gluon in the target nucleus and produce a pair of charm quarks. These charm quarks then fragment and are observed as open charm hadrons ($\rm D^{0}$, $\rm D^{∗}...

518. EPJ Featured Talk: Investigating subnucleonic structures via new measurements of incoherent J/ψ photoproduction in ultra-peripheral Pb–Pb collisions with ALICE

Vendulka Filova (Czech Technical University in Prague (CZ))

08/04/2025, 09:00

Physics of ultraperipheral collisions

Oral

According to quantum chromodynamics, at high energy, hadrons exhibit a dynamic equilibrium between gluon splitting and recombination, known as saturation. Diffractive photonuclear production of J/ψ vector mesons provides unique insights into the gluon distribution of hadrons. The Mandelstam-t variable, representing the momentum transfer, probes hadron structure within the impact-parameter...

452. Measurements of $J/\psi$ and impact of coincident photon induced processes in ultra-peripheral Pb+Pb collisions at $\sqrt{s_\mathrm{NN}}=5.36$ TeV with the ATLAS detector

Mateusz Dyndal (AGH University of Krakow)

08/04/2025, 09:20

Physics of ultraperipheral collisions

Oral

The fully stripped ions used in heavy ion collisions at the LHC are an excellent source of high-energy quasi-real photons. These can interact with photons emitted by the oncoming nucleus, or with the nucleus itself, either directly in inelastic processes or diffractively via pomeron exchange. Diffractive photonuclear processes can produce exclusive vector mesons that are uniquely sensitive...

449. Measurement of dijet production, strange particle production, and bulk properties in photonuclear collisions with ATLAS

Benjamin Jacob Gilbert (Lawrence Livermore Nat. Laboratory (US))

08/04/2025, 09:40

Physics of ultraperipheral collisions

Oral

In ultra-relativistic heavy ion collisions, the charged ions produce an intense flux of equivalent photons. Photon-induced processes are the dominant interaction mechanism when the colliding nuclei have an impact parameter larger than the nuclear diameter. In these ultra-peripheral collisions (UPCs), the photon provides a clean, energetic probe of the partonic structure of the nucleus,...

162. Neutron emission from the photon-induced reactions in UPC of heavy ions - impact of new ALICE data

Antoni Szczurek

08/04/2025, 10:00

Physics of ultraperipheral collisions

Oral

The ultraperipheral collisions are a source of various interesting phenomena based on photon-induced reactions. We calculate cross sections for single and any number of n, p, $\alpha$, $\gamma$ in ultraperipheral heavy-ion collision for LHC energies emitted in forward/backward directions. We analyze the production of a given number of neutrons relevant for a recent ALICE experiment [1] using...