Light-by-light scattering in ultraperipheral heavy ion collisions -- new possibilities

TL;DR

This paper explores new experimental possibilities for observing light-by-light scattering in ultraperipheral heavy ion collisions, emphasizing low transverse momentum and invariant mass regions to detect various mechanisms and resonance contributions.

Contribution

It introduces theoretical predictions for observing multiple photon scattering mechanisms and analyzes background contamination for future detector experiments.

Findings

Identification of photon scattering mechanisms at low $p_{t, ext{γ}}$ and $M_{ ext{γγ}}$

Importance of low diphoton mass measurements for light meson studies

Analysis of background contamination for future detectors

Abstract

Light-by-light scattering is a relatively new area of experimental physics. Our recent, theoretical research shows that studying two photon measurements in regions with lower transverse momentum ($p_{t,\gamma}$) and invariant mass ($M_{\gamma\gamma}$) allows us to observe not only the main contribution of photon scattering, known as fermionic loops but also mechanisms like the VDM-Regge (double-photon hadronic fluctuation). In addition, diphoton measurements at low diphoton masses are crucial for studies of light meson resonance contributions in $\gamma\gamma \to \gamma\gamma$ scattering. We also focus on the interference between different contributions. For future experiments with the ALICE FoCal and ALICE-3 detectors, we have calculated background contamination and have explored possibilities to minimize their impact.