Conveners
Two-photon interactions
- James Brandenburg (Ohio State University)
- Mariola Kłusek-Gawenda (IFJ PAS)
Two-photon interactions
- Christophe Royon (The University of Kansas (US))
- Klaudia Maj (AGH University of Krakow (PL))
We will discuss photon photon physics at the LHC when protons are intact in the final state and can be detected in PPS (CMS) or AFP (ATLAS). We will review the sensitivities to quartic anomalous couplings and the search for axion-like particles in pp collisions. In addition, we will present the complementary gamma gamma physics at lower masses in heavy ion collisions.
Relativistic heavy-ion beams at the LHC are accompanied by a large flux of equivalent photons, leading to multiple photon-induced processes. This talk presents a series of measurements of dilepton production from photon fusion performed by the ATLAS Collaboration. Recent measurements of exclusive dielectron production in ultra-peripheral collisions (UPC) are presented. These processes provide...
Relativistic ultra-peripheral heavy-ion collisions (UPCs) generate an extremely intense electromagnetic field, offering an ideal setting for investigating the electromagnetic excitation of the vacuum. The lowest-order QED excitation involves the creation of lepton pairs through two-photon fusion, commonly referred to as the Breit-Wheeler (BW). In this presentation, we will report a...
The Lorentz-boosted electromagnetic field, arising from colliding nuclei, can be treated as a flux of quasi-real photons. Consequent photonuclear ($\propto$ $Z^{2}$) and photon-photon ($\propto$ $Z^{4}$) processes could reasonably explain the observed enhancements of $J/\psi$ and $e^{+}e^{-}$ pair production at very low transverse momenta ($p_{T}$) in peripheral heavy-ion collisions. The STAR...
Ultraperipheral nucleus-nucleus collisions produce very large photon fluxes such that fundamental quantum-mechanical processes can be observed and studied in a novel way. In this presentation, an observation of the $\tau$ lepton photoproduction at LHC is reported, using ultraperipheral lead-lead collision data collected by CMS. This measurement paves the way for a precise determination of the...
We study the production of $2\pi^+2\pi^-$ in ultraperipheral heavy-ion collisions at RHIC and LHC energies. The recent H1 preliminary data [1] are utilized to improve the description of the poorly known $\gamma p \to 4\pi^\pm p$ process. Predictions for photon-nucleus interactions were calculated for various excited states of $\rho$ meson. We will present an agreement of theory with the...
Relativistic heavy-ion collisions generate extremely strong electromagnetic fields, providing an ideal environment to study the electromagnetic excitation of the vacuum. The Breit-Wheeler process, the lowest-order decay mode of the QED vacuum excitation into electron-positron pairs, has been experimentally verified by the STAR collaboration, stimulating further investigations of higher-order...
In 2017, the ATLAS collaboration published an article that confirmed the experimental phenomenon of light-by-light scattering [1]. This process entails the creation of photon pairs as a consequence of the interaction between strong electromagnetic fields. The effect was successfully recorded through the intense photon flux generated during ultra-peripheral collisions of heavy ions. Two...
