Impact of Sommerfeld Effect and Bound State Formation in Simplified $t$-Channel Dark Matter Models

TL;DR

This paper highlights the significance of Sommerfeld effect and bound state formation in $t$-channel dark matter models, showing their impact on relic abundance predictions and experimental constraints, thus emphasizing the models' testability.

Contribution

It demonstrates the necessity of including non-perturbative effects in relic abundance calculations for simplified dark matter models, challenging previous assumptions of flat correction factors.

Findings

Non-perturbative effects significantly alter relic abundance predictions.

Parameter space remains viable despite direct detection and LHC constraints.

Future experiments can nearly close all remaining detection windows.

Abstract

The existence of a dark matter model with a rich dark sector could be the reason why WIMP dark matter has evaded its detection so far. For instance, colored co-annihilation naturally leads to the prediction of heavier dark matter masses. Importantly, in such a scenario the Sommerfeld effect and bound state formation must be considered in order to accurately predict the relic abundance. Based on the example of the currently widely studied $t$-channel simplified model with a colored mediator, we demonstrate the importance of considering these non-perturbative effects for correctly inferring the viable model parameters. We emphasize that a flat correction factor on the relic abundance is not sufficient in this context. Moreover, we find that parameter space thought to be excluded by direct detection experiments and LHC searches remains still viable. Additionally, we illustrate that long-lived particle searches and bound-state searches at the LHC can play a crucial role in probing such a model. We demonstrate how future direct detection experiments will be able to close almost all of the remaining windows for freeze-out production, making it a highly testable scenario.