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

TL;DR

This paper reports a search for magnetic monopoles in ultraperipheral Pb+Pb collisions at the LHC using a novel detection method, setting new upper limits on monopole production cross-sections in the 20-150 GeV mass range.

Contribution

It introduces a new methodology for detecting highly ionizing particles in heavy-ion data and provides the first limits on monopole pair production in this context.

Findings

No significant monopole signal was observed.

Upper limits on monopole production cross-section were established.

The limits improve previous bounds for low-mass monopoles.

Abstract

This Letter presents a search for highly ionizing magnetic monopoles in 262$~\mu$b$^{-1}$ of ultraperipheral Pb+Pb collision data at $\sqrt{s_{_\textrm{NN}}}=5.36$ 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.