Search for magnetic monopole pair production in ultraperipheral Pb+Pb collisions at $\sqrt{s_{{}_{\text{NN}}}}=5.36$ TeV with the ATLAS detector at the LHC

Abstract

This Letter presents a search for highly ionizing magnetic monopoles in 262$\mu$b${}^{-1}$ of ultraperipheral Pb+Pb collision data at $\sqrt{s_{{}_{\text{NN}}}}=5.36$ TeV collected by the ATLAS detector at the LHC. A new methodology that exploits the properties of clusters of hits reconstructed in the innermost silicon detector layers is introduced to study highly ionizing particles in heavy-ion data. No significant excess above the background, which is estimated using a data-driven technique, is observed. Using a nonperturbative semiclassical model, upper limits at 95% confidence level are set on the cross-section for pair production of monopoles with a single Dirac magnetic charge in the mass range of 20-150 GeV. The search significantly improves on the previous cross-section limits for production of low-mass monopoles in ultraperipheral Pb+Pb collisions.

34 pages in total, author list starting page 17, 3 figures, published in Phys. Rev. Lett. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2023-01/