Dark matter physics in dark $SU(2)$ gauge symmetry with non-Abelian kinetic mixing

TL;DR

This paper explores a dark sector model with non-Abelian $SU(2)_D$ gauge symmetry, discussing its symmetry breaking, dark matter candidate, and potential collider signatures involving dark scalars and gauge bosons.

Contribution

It introduces a novel dark sector model with non-Abelian gauge symmetry, symmetry breaking to $Z_2$, and detailed collider phenomenology predictions.

Findings

Dark matter candidate is a stable fermion from $SU(2)_D$ doublet.

Unique LHC signatures include dark scalar decays into fermions and dark gauge bosons.

Model connects dark and visible sectors via scalar and gauge kinetic mixing.

Abstract

We investigate a model of dark sector based on non-Abelian $SU(2)_D$ gauge symmetry. This dark gauge symmetry is broken into discrete $Z_2$ via vacuum expectation values of two real triplet scalars, and an $SU(2)_D$ doublet Dirac fermion becomes $Z_2-$odd particles whose lighter component makes stable dark matter candidate. The standard model and dark sector can be connected via the scalar mixing and the gauge kinetic mixing generated by higher dimensional operators. We then discuss relic density of dark matter and implications to collider physics in the model. The most unique signatures of this model at the LHC would be the dark scalar ($\Phi_1^{(')}$) productions where it subsequently decays into : (1) a fermionic dark matter ($\chi_l$) and a heavy dark fermion ($\chi_h$) pair, $\Phi_1^{(')} \to \bar \chi_l \chi_h(\bar \chi_h \chi_l) $, followed by $\chi_h$ decays into $\chi_l$ and non-Abelian dark gauge bosons ($X_i$'s) which decays into SM fermion pair $\bar f_{SM} f_{SM}$ resulting in the reaction $p p \rightarrow \Phi_1^{(')} \rightarrow \bar \chi_h \chi_l (\bar \chi_l \chi_h) \to f_{SM} \bar f_{SM} \chi_l \bar \chi_l $, (2) a pair of $X_i$'s followed by $X_i$ decays into a DM pair or the SM fermions resulting in the reaction, $p p \rightarrow \Phi_1^{(')} \rightarrow X_i X_i \rightarrow \bar \chi_l \chi_l f_{SM} \bar f_{SM}$ or even number of $f_{SM} \bar{f}_{SM}$ pairs.