Hadrophilic Z':a bridge from LEP1, SLC and CDF to LEP2 anomalies

Abstract

In order to explain possible departures from the Standard Model predictions for $b\bar b$ and $c\bar c$ production at $Z$ peak, we propose the existence of a $Z'$ vector boson with enhanced couplings to quarks. We first show that this proposal is perfectly consistent with the full set of LEP1/SLC results. In particular, $Z-Z'$ mixing effects naturally explain the fact that $\Gamma_b$ and $\Gamma_c$ deviate from the SM in opposite directions. We then show that there is a predicted range for enhanced $Z'q\bar q$ couplings which explains, for a precise and interesting range of $Z'$ masses, the excess of dijet events seen at CDF. A $Z'$ with such couplings and mass would produce clean observable effects in $b\bar b$ and in total hadronic production at LEP2.