Proceedings: Workshop on Forward Physics and QCD at the LHC, the Future Electron Ion Collider, and Cosmic Ray Physics

These proceedings are the result of the fourth Workshop on Forward Physics and QCD at the LHC, the Future Electron Ion Collider, and Cosmic Ray Physics, held November 18-21 2019 in Guanajuato, Mexico. Previous meetings were held in Nagoya, Japan (2015, 2017), and Stony Brook, New York (2018). The main purpose of the Workshop on Forward Physics and QCD at the LHC, the Future Electron Ion Collider, and Cosmic Ray Physics, held November 18-21 2019 in Guanajuato, Mexico, was to stimulate discussions between experimentalists and theorists in forward hadronic physics, quantum chromodynamics at low-x, diffractive processes, parton saturation effects, and exciting problems in cosmic ray physics. There was special emphasis on physics accessible at the CERN Large Hadron Collider, the Brookhaven National Laboratory Relativistic Heavy Ion Collider, the future U.S. Electron Ion Collider, and cosmic ray physics experiments.