gamma-UPC: Automated generation of exclusive photon-photon processes in ultraperipheral proton and nuclear collisions with varying form factors

TL;DR

This paper introduces gamma-UPC, an automated framework integrated into Monte Carlo tools for generating and calculating cross sections of exclusive photon-photon processes in ultraperipheral collisions, enabling detailed predictions and comparisons with collider data.

Contribution

The paper presents the first automated method for generating exclusive photon-photon processes in ultraperipheral collisions with varying form factors, integrated into existing Monte Carlo codes.

Findings

Validated cross section calculations against LHC data.

Produced predictions for various resonance and particle pair productions.

Demonstrated the framework's capability for future electroweak correction implementations.

Abstract

The automated generation of arbitrary exclusive final states produced via photon fusion in ultraperipheral high-energy collisions of protons and/or nuclei is implemented in the MadGraph5_aMC@NLO and HelacOnia Monte Carlo codes. Cross sections are calculated in the equivalent photon approximation using $\gamma$ fluxes derived from electric dipole and charge form factors, and incorporating hadronic survival probabilities. Multiple examples of $\gamma\gamma$ cross sections computed with this setup, named gamma-UPC, are presented for proton-proton, proton-nucleus, and nucleus-nucleus ultraperipheral collisions (UPCs) at the Large Hadron Collider and Future Circular Collider. Total photon-fusion cross sections for the exclusive production of spin-0,2 resonances (quarkonia, ditauonium, and Higgs boson; as well as axions and gravitons), and for pairs of particles ($J/\psi J/\psi$, WW, ZZ, Z$\gamma$, $t\bar{t}$, HH) are presented. Differential cross sections for exclusive dileptons and light-by-light scattering are compared to LHC data. This development paves the way for the upcoming automatic event generation of any UPC final state with electroweak corrections at next-to-leading-order accuracy and beyond.