FIG. 2 .
2Neutron multiplicity dependence of (upper) hα core i and (lower) hm μμ i of μ þ μ − pairs in ultraperipheral Pb-Pb collisions at ffiffiffiffiffiffiffiffi s NN p ¼ 5.02 TeV. The vertical lines on **data** points depict the statistical uncertainties, while the systematic uncertainties of the **data** are shown as shaded areas. The dot-dashed line shows the STARLIGHT prediction, and the dashed line corresponds to the leading-order QED calculation of Ref.[48].
