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

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 by including a global Peccei-Quinn symmetry, also furnishes two components of dark matter that satisfy observer relic density without fine-tuning of model parameters. Furthermore, this model provides a rich phenomenology by introducing a vector-like quark whose presence can be sensed in collider experiments and dark matter production mechanisms. We explore the possibility of democratic Yukawa interaction of the vector-like quark with all up-type quarks and scalar dark matter candidate. We also employ next-to-leading order NLO-QCD correction for VLQ pair production to study a unique search at the LHC, generating a pair of boosted tops with sizeable missing transverse momentum. Multivariate analysis with jet substructure variables has a strong ability to explore a significant parameter space of this model at the 14 TeV LHC.