Rare decays with missing energy and new invisible scalars

Abstract: We discuss possible light invisible scalars in the context of rare decays with missing energy. We first explore the windows remaining in B to K + inv and K to pi + inv decay modes. We construct simple UV-complete extensions and discuss some resulting phenomenology in parameter regions where the scalars are consistent with dark matter constraints. For these and heavier scalars, we study the consequences of these models in monojet events.