Foreword

Abstract

These are the Proceedings of the scientific activities of CORFU2021, the 20th Hellenic School and Workshops on Elementary Particle Physics and Gravity, which took place from August 29th to October 9th, 2021. The Workshops were hosted by the European Institute for Sciences and their Applications (EISA) in the conference center of the former Royal Palace Garden of Mon Repos in Corfu, Greece. The Corfu2021 activities consisted of one School and seven Workshops, bringing together world-class scientists and young researchers to interact and forge new collaborations. Specifically, the CORFU2021 hosted the following sessions: • Workshop on the Standard Model and Beyond, • Workshop on Celestial Amplitudes and Flat Space Holography, • Workshop on New Developments in Quantum Gravity and String Theory, • Workshop on Quantum Features in a de Sitter Universe, • Humboldt Kolleg on Quantum Gravity and Fundamental Interactions, • Workshop on Quantum Geometry, Field Theory and Gravity, • School on Quantum Gravity Phenomenology in the Multi-Messenger Approach, • Workshop on Quantum Gravity Phenomenology in the Multi-Messenger Approach.