Omar Observation of gamma gamma -> tau+tau- in proton-proton collisions and limits on the anomalous electromagnetic moments of the tau lepton The photon-induced production of a pair of τ leptons, γγ→ττ, is observed for the first time in proton-proton collisions. The observation is based on a data set recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb−1. Events with a small number of tracks close to the di-τ vertex are selected to isolate photon-induced processes. Limits on the anomalous electromagnetic moments of the τ lepton originating from potential new physics effects on the γττ vertex are also set.