Monojets from compressed weak frustrated dark matter

TL;DR

This paper explores a modified Higgs triplet model with additional fermions, proposing it can explain monojet excesses and dark matter relic abundance while remaining consistent with collider constraints.

Contribution

It introduces a weak triplet of Dirac fermions and a neutral fermion X, providing a unified framework for dark matter and collider anomalies within a frustrated dark matter paradigm.

Findings

The model can produce a compressed fermion spectrum compatible with monojet excesses.

The neutral fermion X can serve as a viable thermal dark matter candidate.

The model evades multijet constraints while explaining monojet signals.

Abstract

We extend the so-called hyperchargeless Higgs triplet model to include a weak triplet of Dirac fermions and a Dirac fermion $X$ transforming trivially under the Standard Model gauge group. We are motivated in part by a collection of anomalies that can be interpreted as a new scalar state with mass of approximately 152 GeV coupling to $W$ but not $Z$ bosons, which may be consistent with the electrically neutral triplet scalar in this model (provided that it mixes very slightly with the Standard Model Higgs boson). Meanwhile, the lightest neutral fermion in the model is stable and can be thermal dark matter with the correct relic abundance if it mixes lightly with the neutral triplet fermion, such that the dark matter is composed mostly of $X$. Because $X$ couples to the Standard Model only through a Yukawa-like interaction with the pair of triplets, this model falls into the frustrated dark matter paradigm. Finally, the spectrum of exotic fermions in this model can exhibit the strong compression favored by the current excess in the monojet channel, and evades multijet constraints in the region favored by monojets. In this work we explore this model's phenomenology and compare the parameter space regions best suited to each of the aforementioned excesses and constraints.