Precision prediction of a democratic up-family philic KSVZ axion model at the LHC

TL;DR

This paper investigates a KSVZ axion model extended with a scalar dark matter candidate and vector-like quarks, analyzing its collider signatures at the LHC with NLO-QCD corrections and jet substructure techniques.

Contribution

It introduces a democratic Yukawa interaction framework for VLQ and dark matter, and performs a detailed collider analysis including NLO corrections and multivariate techniques.

Findings

NLO-QCD corrections significantly reduce theoretical uncertainties.

The analysis identifies viable parameter space for detection at the 14 TeV LHC.

Boosted top jet signatures with missing energy are promising for discovery.

Abstract

In this work, we study the $SU(2)_L$ singlet complex scalar extended KSVZ model that, in addition to providing a natural solution to the strong-CP problem, furnishes two components of dark matter that satisfy observer relic density without fine-tuning the model's parameters. A colored vector-like quark (VLQ) is naturally present in the KSVZ axion model, providing a rich dark matter and collider phenomenology. In this extended model, scalar dark matter interacts with the Standard Model up-type quarks (up, charm, top) through VLQ. We explore the possibility of democratic Yukawa interaction of the VLQ with all up-type quarks and scalar dark matter candidate. We also employ next-to-leading order NLO-QCD correction on dominant production channels for VLQ pair production to study a unique search at the LHC, generating a pair of boosted tops with sizeable missing transverse momentum. Such corrections are significant and reduce factorization and renormalization scale uncertainties substantially. The NLO fixed order results are matched with the Pythia8 parton shower. After being pair-produced, each VLQ decays into a dark matter and a top quark. We conducted a multivariate analysis using jet substructure variables of boosted top fatjets with a significant missing transverse momentum signal. This analysis allows us to explore a substantial parameter space of this model at the 14 TeV LHC.