Remarks on the Z' Drell-Yan cross section

TL;DR

This paper revisits the theoretical calculation of the Z' boson production cross section in Drell-Yan processes, revealing a significant discrepancy in the standard formula used in experimental limits, which impacts current search constraints.

Contribution

The authors derive the correct formula for the Z' Drell-Yan cross section, correcting a factor of 8 discrepancy in the literature, and discuss implications for experimental analyses.

Findings

Standard formula underestimates the cross section by a factor of 8.

Revised calculations affect existing experimental limits on Z' models.

Encourages re-evaluation of past experimental results using the corrected formula.

Abstract

Many extension of the standard model contain an extra U(1)' gauge group with a heavy Z' gauge boson. Perhaps the most clear signal for such a Z' 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', 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 re-examine analyses that have used this formula.