Ultra-High-Energy Cosmic-Rays (UHECR): at the Intersection of the Cosmic and Energy Frontiers - Overview of the Snowmass UHECR white paper and roadmap

As part of the US "Snowmass" community planning exercise, the UHECR community has come together to write a comprehensive white paper discussing the recent progress and open questions in the field, as they relate to the overarching goals of particle and astroparticle physics. The document outlines strategies and recommendations for answering these questions over the next two decades. It also proposes an integrated timeline, which considers the progress expected to be achieved by the upgraded Pierre Auger Observatory and Telescope Array experiment in this decade, and the need for a set of complementary next-generation experiments combining high-accuracy measurements (GCOS, IceCube-Gen2 with its surface array) and very high exposure at the highest energies (GRAND, POEMMA) in the next decade. The resulting document, entitled "Ultra-High Energy Cosmic-Rays: at the Intersection of the Cosmic and Energy Frontiers", appears as a special issue of Astroparticle Physics (Astropart. Phys. 149 (2023) 102819 - arXiv:2205.05845). This contribution provides a summary of the document with a focus on (selected) recommendations and proposed roadmap.