K+K- photoproduction in ultra$-$peripheral Pb$--$Pb collisions

In ultra-peripheral collisions (UPCs) of relativistic heavy ions, photoproduction occurs when a photon emitted from one nucleus interacts with the other nucleus from the opposing beam, producing particles in the final state. Measurements of \KK photoproduction probe interactions and couplings between the $\phi (1020)$ and charged kaons with photons and nuclear targets. We report exclusive \KK photoproduction cross section at midrapidity in \PbPb collisions at \snn = 5.02 TeV, which is measured for the first time in UPCs.