Baryonic Z' Explanation for the CDF Wjj Excess

Understand

The latest CDF anomaly, the excess of dijet events in the invariant-mass window 120-160 GeV in associated production with a $W$ boson, can be explained by a baryonic $Z'$ model in which the $Z'$ boson has negligible couplings to leptons.

• Although this $Z'$ model is hardly subject to the Drell-Yan constraint from Tevatron, it is constrained by the dijet data from UA2 ($\sqrt{s} = 630$ GeV), and the precision measurements at LEP through the mixing with the SM $Z$ boson.
• We show that under these constraints this model can still explain the excess in the M_{jj} \sim 120 - 160 GeV window, as well as the claimed cross section $\sigma(W Z') \sim 4$ pb.
• Implications at the Tevatron would be the associated production of $\gamma Z',\; Z Z'$, and $Z'Z'$ with the $Z' \to jj$.