The PPS (Precision Proton Spectrometer) detector system consists of silicon tracking stations as well as timing detectors to measure both the position and direction of protons and their time-of-flight with high precision. They are located at around $200\textrm{-}220\,\textrm{m}$ from the interaction point in the very forward region on both sides of the CMS experiment.
The PPS detector is built to study central exclusive production (CEP) in proton-proton collisions at the LHC, including the photon-photon production of W and Z boson pairs, high-mass photon and lepton pairs, high-$p_T$ jet production, as well as searches for anomalous couplings and new resonances.
The PPS detector system has taken data at high luminosity while fully integrated to the CMS experiment. The total data collected correspond to around $100\,{\rm fb}^{-1}$ during the LHC Run 2, from 2016-2018.
For the first time, exclusive production of lepton pairs has been observed in the CMS detector while one outgoing proton is measured in PPS using roughly $10\,{\rm fb}^{-1}$ of data accumulated in 2016 during high-luminosity LHC operation. These first results show a good understanding, calibration and alignment of the PPS detectors.