The exploration of physics beyond the Standard Model (BSM) via effective field theories (EFTs) has taken center stage in recent years, and is likely to be a key ingredient of the high-energy theoretical and experimental programs over the coming decade. On the other hand, in the past few years, amplitude methods have significantly extended our understanding of EFTs defined just by the particle content and certain on-shell ``building-blocks,” without recourse to Lagrangians. The on-shell perspective has allowed to enlarge the landscape of EFTs, revealing fascinating new aspects such as color(flavor)-kinematics dualities and hidden geometric structures.
Some of these new insights already provided very useful information for the BSM community. One example is the use of constraints from causality and unitarity to carve out the space of consistent EFTs that can be UV-completed. Another example is the on-shell formulation of massive EFTs which not only is useful for collider phenomenology, but also may provide new insights into the Higgs mechanism and the electroweak hierarchy problem.
The purpose of the workshop is to bring together experts on Amplitude Methods and BSM to discuss these emergent lines of research, and hopefully create new ones. We hope the workshop will bridge these two communities and encourage cross-fertilization.