On-shell effective theory for higher-spin dark matter

TL;DR

This paper introduces an on-shell amplitude approach for higher-spin dark matter, simplifying calculations and providing new insights into production mechanisms and phenomenology without relying on traditional Lagrangian methods.

Contribution

It develops an on-shell amplitude framework for higher-spin dark matter, enabling efficient process calculations and deeper physical understanding of production and decay channels.

Findings

Applicable to a broad mass range from sub-TeV to GUT scale

Analyzes gravitational and Higgs-mediated production scenarios

Predicts decay signatures for higher-spin dark matter

Abstract

We apply the on-shell amplitude techniques in the domain of dark matter. Without evoking fields and Lagrangians, an effective theory for a massive spin-$S$ particle is defined in terms of on-shell amplitudes, which are written down using the massive spinor formalism. This procedure greatly simplifies the study of theories with a higher-spin dark matter particle. In particular, it provides an efficient way to calculate the rates of processes controlling dark matter production, and offers better physical insight into how different processes depend on the relevant scales in the theory. We demonstrate the applicability of these methods by exploring two scenarios where higher-spin DM is produced via the freeze-in mechanism. One scenario is minimal, involving only universal gravitational interactions, and is compatible with dark matter masses in a very broad range from sub-TeV to the GUT scale. The other scenario involves direct coupling of higher-spin DM to the Standard Model via the Higgs intermediary, and leads to a rich phenomenology, including dark matter decay signatures.