Dark sector shining through 750 GeV dark Higgs boson at the LHC

TL;DR

This paper explores a dark sector model with a dark Higgs boson around 750 GeV that can be produced at the LHC, decay into photons, and account for dark matter relic density without conflicting with current experimental constraints.

Contribution

It proposes a novel dark sector model featuring a dark Higgs boson that explains the 750 GeV resonance and dark matter properties simultaneously.

Findings

Dark Higgs boson can be produced via dark quark loops at the LHC.

Decay width of the dark Higgs can be around 45 GeV due to dark photon decays.

Dark scalar dark matter can achieve the correct relic density without violating detection bounds.

Abstract

We consider a dark sector with $SU(3)_C \times U(1)_Y \times U(1)_X$ and three families of dark fermions that are chiral under dark $U(1)_X$ gauge symmetry, whereas scalar dark matter $X$ is the SM singlet. $U(1)_X$ dark symmetry is spontaneously broken by nonzero VEV of dark Higgs field $\langle \Phi \rangle$, generating the masses of dark fermions and dark photon $Z^\prime$. The resulting dark Higgs boson $\phi$ can be produced at the LHC by dark quark loop (involving 3 generation) and will decay into a pair of photon through charged dark fermion loop. Its decay width can be easily $\sim 45$ GeV due to its possible decays into a pair of dark photon, which is not strongly constrained by the current LHC searches $pp \rightarrow \phi \rightarrow Z^\prime Z^\prime$ followed by $Z^\prime$ decays into the SM fermion pairs. The scalar DM can achieve thermal relic density without conflict with direct detection bound or the invisible $\phi$ decay into a pair of DM.