Remarks on the $Z^{\prime }$ Drell-Yan cross section

Many extensions of the standard model contain an extra $U(1{)}^{\prime }$ gauge group with a heavy $Z^{\prime }$ gauge boson. Perhaps the most clear signal for such a $Z^{\prime }$ would be a resonance in the invariant mass spectrum of the lepton pairs to which it decays. In the absence of such a signal, experiments can set limits on the couplings of such a $Z^{\prime }$, using a standard formula from theory. We repeat its derivation and find that, unfortunately, the standard formula in the literature is a factor of 8 too small. We briefly explore the implication for existing experimental searches and encourage the high-energy physics community to reexamine analyses that have used this formula.

Figure 1

Left-hand side: Our $c_u-c_d$ exclusion plot based on the D0 data [20] and Eq. (10). Right-hand side: Reference [10] $c_u-c_d$ exclusion plot based on the D0 data [20] and Eq. (1).