Spencer Robert Klein | Searcharxiv

arXiv2026

Ultra-peripheral Collisions

Photons in ultra-peripheral collisions of heavy ions (and protons) can be used for a variety of physics purposes - for studies of nuclear structure at low Bjorken$-x$, as probes of beyond-standard-model physics at the highest possible photon energies, and to explore new regimes of quantum mechanics via interferometry between two photon sources that share no common origin. This review will present the origins of photons in ultra-peripheral collisions and discuss the important physics that is being done with these photons, with particular emphasis on those on the energy frontier for photon physics.

hep-ex↗

arXiv2022

White Paper on Forward Physics, BFKL, Saturation Physics and Diffraction

The goal of this whitepaper is to give a comprehensive overview of the rich field of forward physics. We discuss the occurrences of BFKL resummation effects in special final states, such as Mueller-Navelet jets, jet gap jets, and heavy quarkonium production. It further addresses TMD factorization at low x and the manifestation of a semi-hard saturation scale in (generalized) TMD PDFs. More theoretical aspects of low x physics, probes of the quark gluon plasma, as well as the possibility to use photon-hadron collisions at the LHC to constrain hadronic structure at low x, and the resulting complementarity between LHC and the EIC are also presented. We also briefly discuss diffraction at colliders as well as the possibility to explore further the electroweak theory in central exclusive events using the LHC as a photon-photon collider.

hep-ph↗