We explore the dark matter and collider phenomenology of the minimal gauged ${\mathrm{U}(1)}_{\mathrm{B}}$ model, consisting of a leptophobic $Z_{\mathrm{B}}$ gauge boson, and an accompanying Higgs $S_{\mathrm{B}}$. By requirement of anomaly cancellation, the fermion sector naturally contains a dark matter candidate—a Majorana isosinglet $\chi$ stabilized by an inherent $Z_2$ symmetry. The absence of evidence for $Z$ prime dijet resonances at the LHC suggests that the scale of symmetry breaking is ${\mathrm{\Lambda }}_{\mathrm{B}}\gtrsim 500\mathrm{GeV}$. Saturation of dark matter abundance together with limits on the direct detection cross section (dominated by Higgs exchange) constrains the Higgs mixing angle to $|\theta |\lesssim 0.22$. For small mixing angles of $|\theta |\lesssim {10}^{-3}$, the $\mathcal{O}(10\%)$ branching fractions of the fermion loop-mediated $S_{\mathrm{B}}\to \gamma \gamma$, $Z\gamma$, $ZZ$ modes may provide clues about the fermion content of the model at the LHC.

• Received 25 June 2015

DOI:https://doi.org/10.1103/PhysRevD.92.055020