Speaker
Description
Ultra-peripheral heavy-ion collisions (UPC) at the Large Hadron Collider provide a unique environment to study high-energy photon-induced interactions. The intense electromagnetic fields of relativistic nuclei enable a broad physics program encompassing both photon–photon and photon–nucleus processes. In this talk, recent UPC results from the four LHC collaborations are reviewed. Photon–photon interactions offer a clean and precisely calculable environment to test quantum electrodynamics and to search for rare or beyond-the-Standard-Model phenomena. Photon–nucleus interactions provide direct sensitivity to the partonic structure of nuclei, in particular the gluon density at small momentum fractions, thereby probing quantum chromodynamics over a broad kinematic range. Emerging measurements also report intriguing indications of collective behavior in photon-induced systems, raising new questions about the origin of collectivity in such systems. Together, these results highlight the versatility of UPC as a precision tool for both QED and QCD studies, and as a probe of novel phenomena at high energies.