Accessing Masses Beyond Collider Reach - in EFT

TL;DR

This paper explores how effective field theory can be used to infer the masses of new particles beyond collider reach by analyzing correlations between observables with different scaling properties, despite inherent model dependencies.

Contribution

It introduces a method to extract masses of unseen states in EFT by studying observable correlations, lifting degeneracies in parameter space without fixing coupling strengths.

Findings

Correlations can reveal masses beyond direct detection.

Certain observables are more sensitive for mass inference.

Perturbativity and existing limits constrain possible deviations.

Abstract

We demonstrate how masses of new states, beyond direct experimental reach, could nevertheless be extracted 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 $g_\ast$ vs. $M$ plane is lifted by studying correlations between observables that depend on operators with a different $\hbar$ 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. In particular, 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.