Unveiling desert region in inert doublet model assisted by Peccei-Quinn symmetry

TL;DR

This paper explores a dark matter model combining WIMP and axion components within an inert doublet framework assisted by Peccei-Quinn symmetry, analyzing collider signatures at the LHC with NLO QCD corrections.

Contribution

It introduces a novel dark sector model with combined axion and WIMP components, and investigates VLQ production and decay signatures at the LHC with advanced analysis techniques.

Findings

Model satisfies observed DM relic density.

Potential to exclude large parameter space at LHC with 300 fb^{-1}.

Enriches IDM phenomenology with PQ symmetry and axion-WIMP coexistence.

Abstract

The Inert Higgs Doublet model (IDM), assisted by Peccei-Quinn (PQ) symmetry, offers a simple but natural framework of a dark sector that accommodates Weakly Interacting Massive Particle (WIMP) and axion as dark matter components. Spontaneous breaking of $U(1)_{PQ}$ symmetry, which was originally proposed as an elegant solution to the strong charge-parity (CP) problem, also ensures the stability of WIMP through a residual $\mathbb{Z}_2$ symmetry. Interestingly, additional fields necessitated by PQ symmetry further enrich the dark sector. These include a scalar field proprietor for axion DM and a vector-like quark (VLQ) that acts as a portal for the dark sector through Yukawa interactions. Moreover, this combination of the axion and WIMP components satisfies the observed DM relic density and reopens the phenomenologically exciting region of the IDM parameter space where the WIMP mass falls between 100 - 550 GeV. We investigate the model-independent pair production of VLQs exploring this region at the Large Hadron Collider (LHC), incorporating the effects of next-to-leading order (NLO) QCD corrections. After production, each VLQ decays into a top or bottom quark accompanied by an inert scalar, a consequence of the residual $\mathbb{Z}_2$ symmetry. Utilising relevant observables with a leptonic search channel and employing multivariate analysis, we demonstrate the ability of this analysis to exclude a significant portion of the parameter space with an integrated luminosity of 300 $\text{fb}^{-1}$.