Observation of forward neutron multiplicity dependence of dimuon acoplanarity in ultraperipheral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV

CMS Collaboration

The first measurement of the dependence of $\gamma \gamma$ $\to$ ${\mu }^{+}{\mu }^{-}$ production on the multiplicity of neutrons emitted very close to the beam direction in ultraperipheral heavy ion…