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 Z(B) gauge boson, and an accompanying Higgs S-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 Lambda(B) greater than or similar to 500 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 vertical bar theta vertical bar less than or similar to 0.22. For small mixing angles of vertical bar theta vertical bar less than or similar to 10(-3), the O(10%) branching fractions of the fermion loop-mediated S-B -> gamma gamma, Z gamma, ZZ modes may provide clues about the fermion content of the model at the LHC.