Speaker
Description
The intense photon fluxes of relativistic nuclei provide a possibility
to study photonuclear and two-photon interactions in ultra-peripheral collisions (UPC)
where the nuclei do not overlap and no strong nuclear interactions occur.
The study of such collisions provides information about the initial state of nuclei (nPDF).
Exclusive $J/\psi$ production in UPC which is sensitive to the nuclear
gluon distribution: first ALICE results from LHC Run 2 will be presented for
this channel for both forward and mid-rapidity $J/\psi$. The increased statistics
and the higher collision energy allows for a more detailed study of lower values of Bjorken-x.
The analysis of the $\gamma+A \rightarrow \rho^0$+A process in UPC is a tool to test the, so-called, black disk regime
where the target nucleus appears like a black disk and the total $\rho^0$+A cross section reaches it quantum mechanical limit.
ALICE reports new measurements of $\rho^0$ photoproduction cross sections in Pb-Pb UPC at $\sqrt{s_{NN}}=5.02$ TeV
at mid-rapidity which are compared to predictions.
| Experimental Collaboration | ALICE Collaboration |
|---|
