25th International Workshop on Deep Inelastic Scattering and Related Topics

ALICE measurements on rho^0 photoproduction in Pb-Pb ultra-peripheral collisions

4 Apr 2017, 11:20

20m

Small Lecture Theatre, Poynting Building

WG2) Low x and Diffraction WG2 Low x and Diffraction

Speaker

Dr Valeri Pozdnyakov (JINR(Dubna))

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.
Within the Vector-meson Dominance Model (VDM), the rho0 contribution prevails in the QCD photon structure function and the gamma+A -> rho0+A process in heavy-ion UPC is a tool to test the, so-called, black disk regime where the target nuclei appears like a black disk and the total rho0+A cross section reaches its limit. RHIC and first LHC results have deviated from some Glauber+VDM calculations, which thus call for new data.
ALICE reports measurements on rho0 photoproduction cross sections
in Pb-Pb UPC with data taken at sqrt(s_NN)=2.76 TeV and new measurements with the data taken at sqrt(s_NN)=5.02 TeV. The mid-rapidity cross section of coherent rho0 photoproduction is measured,and it is compared to theoretical models.