New Constraints on the Existence of Massive Monopoles in Ultra-Peripheral Heavy Ion Collisions with ATLAS

Abstract

In ultraperipheral Pb+Pb collisions, intense electromagnetic fields enable the generation of magnetic monopole pairs via the Schwinger mechanism. Due to their high ionization and unique trajectories in a solenoidal magnetic field, monopoles are expected to leave numerous clusters in the innermost ATLAS pixel detector without associated reconstructed charged-particle tracks or calorimeter activity. This document presents a search for monopole-pair production in ultraperipheral Pb+Pb collisions with a magnetic charge of $q_{m} = 1 g_{D}$ in the monopole mass range of 20–150 GeV, based on 5.36 TeV data recorded in 2023. The results are compared with a recently developed semiclassical model that includes non-perturbative cross-section calculations -- as well as with a recent search limits obtained by the MoEDAL Collaboration using complementary techniques.