Run 3 luminosity measurements with the Pixel Luminosity Telescope

For Run-3 of the LHC, the CMS experiment has installed the pixel luminosity telescope (PLT) which is made of three layers of pixel sensors that count charged particles from each bunch crossing of the LHC beam. The rate of triple-coincidences between layers is translated into a luminosity value that is published about every 1.4 seconds. In addition, at a lower rate, particle trajectories are reconstructed for systematic studies of beam backgrounds and efficiencies. The paper discussed the working principles of luminosity calibrations and results from systematic studies.