Baryonic Z' Explanation for the CDF Wjj Excess

Abstract

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 $Z^{\prime }$ model in which the $Z^{\prime }$ boson has negligible couplings to leptons. Although this $Z^{\prime }$ 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 $\sigma (W{Z}^{\prime })\sim 4$ pb. Implications at the Tevatron would be the associated production of $\gamma Z^{\prime },Z{Z}^{\prime }$, and $Z^{\prime }{Z}^{\prime }$ with the $Z^{\prime }\to jj$. We show that with tightened jet cuts and improved systematic uncertainties both $\gamma Z^{\prime }\to \gamma jj$ and $Z{Z}^{\prime }\to {\ell }^{+}{\ell }^{-}jj$ channels could be useful to probe this model at the Tevatron.

Comments: 5 pages, 2 figures; Comments added why the current Z jj and gamma jj did not see the excess; matches the published version in PRL