Indirect estimation of masses beyond collider reach — in EFT

Abstract

Abstract We demonstrate how masses of new states, beyond direct experimental reach, could nevertheless be estimated in the framework of effective field theory (EFT), given broad assumptions on the underlying UV physics, however not sticking to a particular setup nor fixing the coupling strength of the scenario. The flat direction in the coupling-vs.-mass plane (g ∗ vs. M) is lifted by studying correlations between observables that depend on operators with a different ℏ scaling. We discuss the remaining model dependence (which is inherent even in the EFT approach to have control over the error due to the truncation of the power series), as well as prospects to test paradigms of UV physics. We provide an assessment of which correlations are best suited regarding sensitivity, give an overview of possible/expected effects in different observables, and demonstrate how perturbativity and direct search limits corner possible patterns of deviations from the SM in a given UV paradigm. In particular, given a certain pattern of deviations from the SM, we address the question whether we actually expect to see the new states at the LHC or the FCC, relying solely on EFT arguments.