Search for Magnetic Monopoles with the MoEDAL Forward Trapping Detector in 13 TeV Proton-Proton Collisions at the LHC

MoEDAL is designed to identify new physics in the form of long-lived highly ionizing particles produced in high-energy LHC collisions. Its arrays of plastic nuclear-track detectors and aluminium trapping volumes provide two independent passive detection techniques. We present here the results of a first search for magnetic monopole production in 13 TeV proton-proton collisions using the trapping technique, extending a previous publication with 8 TeV data during LHC Run 1. A total of 222 kg of MoEDAL trapping detector samples was exposed in the forward region and analyzed by searching for induced persistent currents after passage through a superconducting magnetometer. Magnetic charges exceeding half the Dirac charge are excluded in all samples and limits are placed for the first time on the production of magnetic monopoles in 13 TeV $pp$ collisions. The search probes mass ranges previously inaccessible to collider experiments for up to five times the Dirac charge.

Figure 1

Top: persistent current (in units of $g_D$ after application of a calibration constant) after first passage through the magnetometer for all samples. Bottom: results of repeated measurements of candidate samples with absolute measured values in excess of $0.25g_D$.

Figure 2

Cross-section upper limits at 95% confidence level for DY monopole production in 13 TeV $pp$ collisions as a function of mass for spin-$1/2$ (left) and spin-0 (right) monopoles. The colors correspond to different monopole charges. Acceptance loss is dominated by monopoles punching through the trapping volume for $|g|=g_D$ while it is dominated by stopping in upstream material for higher charges, explaining the shape difference. The solid lines are DY cross-section calculations at leading order.