Hosted by: Oleg Eyser

Exclusive dimuon pairs with invariant mass Mμμ>10 GeV have been measured in ultra-peripheral lead-lead collisions at √sNN=5.02 TeV, using an integrated luminosity of 515 μb−1 taken with the ATLAS detector at the LHC in 2015. These very low-multiplicity interactions were recorded using an experimental trigger requiring a muon, low total transverse energy recorded in the calorimeter system, gaps at forward angles, and a reconstructed track. Events are selected to have no-other final state particles than a pair of opposite-sign dimuons. The cross section for dimuon pairs in Pb+Pb collisions is presented as a function of pair mass (Mμμ) and pair rapidity (Yμμ) and is well-described by calculations of Pb+Pb→Pb(*)+Pb(*)+μ+μ− using STARLIGHT 1.1 calculations. These data will improve the understanding of the strong electromagnetic fields surrounding the nucleus, which enable future UPC measurements utilizing these high energy probes.