Search for physics beyond the Standard Model at the high intensity frontier, from new physics to spin-offs. A trilateral Europe – United States – Japan effort.

BEYOND will explore elusive aspects of the Standard Model (SM) of particle physics and search for new physics, covering a wide range of research topics across different areas of fundamental interactions, from electroweak to strong interactions. It will exploit particle accelerators, as well as shared experimental techniques and search strategies. The observation of neutrino oscillations established a framework consistent with the mixing of three neutrino flavours in three mass eigenstates, along with small mass differences. Experimental anomalies suggest the existence of sterile neutrino states, which participate in the mixing but do not couple to the SM gauge bosons. Lepton mixing and massive neutrinos also provide a potential gateway to deviations from the SM in the lepton sector, including Charged Lepton Flavour Violation. Several low-energy aspects of quark-gluon interactions remain a challenge, such as the mechanism of color confinement, which accounts for 99% of the mass of ordinary matter in the Universe, as well as the equation of state of ultradense matter. Astrophysical observations and particle physics anomalies indicate the existence of Dark Matter (DM), prompting major efforts to the search for galactic DM and potential signals at particle accelerators.We are leading the development, construction, commissioning, operation and data analysis of cutting-edge experiments aimed at answering these fundamental questions. These endeavors require extensive knowledge sharing and technological advancements, with potential spin-offs not only in fundamental physics but also in commercial applications, offering market opportunities for non-academic participants. Through extended exposure to cutting-edge research environments at world-class laboratories, including PSI and CERN (Switzerland), FNAL, JLAB and BNL (United States), and J-PARC (Japan), BEYOND will enhance the career prospects of both researchers and technical staff.