Leptobaryons as Majorana dark matter

We explore the dark matter and collider phenomenology of the minimal gauged U(1)B model, consisting of a leptophobic ZB gauge boson, and an accompanying Higgs SB. By requirement of anomaly cancellation, the fermion sector naturally contains a dark matter candidate---a Majorana isosinglet χ stabilized by an inherent Z₂ symmetry. The absence of evidence for Z prime dijet resonances at the LHC suggests that the scale of symmetry breaking is ΛB500 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 |θ|0.22. For small mixing angles of |θ|10^-3, the O(10%) branching fractions of the fermion loop-mediated SB→γγ, Zγ, $ZZ$ modes may provide clues about the fermion content of the model at the LHC.