This book contains the Proceedings of the Ninth Meeting on CPT and Lorentz Symmetry, held at Indiana University in Bloomington May 17-26, 2022. The Meeting focused on tests of these fundamental symmetries and on related theoretical issues, including scenarios for possible violations. Experimental topics covered at the meeting include astrophysical observations of neutrinos, photons, cosmic rays, pulsars, and gravitational waves; investigations at accelerators and storage rings involving neutral mesons, muons, quarks, and flavor-changing processes; gravity tests in the laboratory and in the solar system; spectroscopic studies of ions, atoms, molecules, and exotic atoms; measurements involving spin motion; comparative tests between matter and antimatter; lasers and masers; measurements involving neutrons; investigations with cavities, oscillators, and resonators; neutrino oscillations, propagation, and endpoint measurements.Theoretical and phenomenological topics discussed involved the identification of signatures for CPT and Lorentz violation in particle physics, electromagnetism, and gravity; mechanisms and toy models for spacetime-symmetry breakdown; studies in field theory, gravitation, and particle physics; and condensed-matter applications.
