Spin portal to dark matter

TL;DR

This paper explores a novel spin portal mechanism for dark matter transforming as a (1,0)⊕(0,1) representation, analyzing its interactions, constraints from invisible decays, and relic density implications.

Contribution

It introduces the spin portal as a new interaction channel for dark matter and evaluates its significance compared to the Higgs portal using experimental data.

Findings

Spin portal effects can dominate over Higgs portal effects.

Dark matter with (1,0)⊕(0,1) structure must have mass > 43 GeV.

Constraints from Z and Higgs invisible widths limit low energy constants.

Abstract

In this work we study the possibility that dark matter fields transform in the $(1,0)\oplus(0,1)$ representation of the Homogeneous Lorentz Group. In an effective theory approach, we study the lowest dimension interacting terms of dark matter with standard model fields, assuming that dark matter fields transform as singlets under the standard model gauge group. There are three dimension-four operators, two of them yielding a Higgs portal to dark matter. The third operator couple the photon and $Z^0$ fields to the higher multipoles of dark matter, yielding a \textit{spin portal} to dark matter. For dark matter ($D$) mass below a half of the $Z^0$ mass, the decays $Z^0\to \bar{D} D$ and $H\to \bar{D}D$ are kinematically allowed and contribute to the invisible widths of the $Z^0$ and $H$. We calculate these decays and use experimental results on these invisible widths to constrain the values of the low energy constants finding in general that effects of the spin portal can be more important that those of the Higgs portal. We calculate the dark matter relic density in our formalism, use the constraints on the low energy constants from the $Z^0$ and $H$ invisible widths and compare our results with the measured relic density, finding that dark matter with a $(1,0)\oplus(0,1)$ space-time structure must have a mass $M>43 ~ GeV$.