Light vectors coupled to anomalous currents with harmless Wess-Zumino terms

TL;DR

This paper explores how light vectors coupled to anomalous currents can be UV completed to suppress harmful IR effects, enabling new collider probes at the LHC.

Contribution

It presents a framework for anomaly-free UV completions with chiral fermions that suppress Wess-Zumino terms, relaxing bounds on light vectors.

Findings

Anomaly cancellation can be achieved with mostly-chiral heavy fermions.

Suppressed Wess-Zumino terms reduce IR bounds on light vectors.

High-luminosity LHC can probe these scenarios via $h o Z \gamma$ and charged lepton searches.

Abstract

We reconsider the case of light vectors coupled to anomalous fermionic currents, focussing on the interplay between UV and IR dynamics. Taking as a general framework the gauging of the Standard Model accidental symmetries, we show that it is possible to devise an anomaly-free UV completion with mostly-chiral heavy fermions such that anomalous Wess-Zumino terms are suppressed in the IR, thus relaxing would-be strong bounds from the longitudinal emission of light vectors coupled to non-conserved currents. We classify such scenarios and show that they will be extensively probed at the high-luminosity phase of the LHC via the measurement of the $h \to Z \gamma$ rate and the direct search for non-decoupling charged leptons.