Precision Electroweak Tensions and a Dark Photon

TL;DR

This paper investigates how variations in electroweak measurements and assumptions influence the fit of the Standard Model, exploring the potential role of a kinetically mixed dark photon and its implications for future collider searches.

Contribution

It analyzes the impact of different assumptions on electroweak observables and explores the phenomenology of dark photons, including their detection prospects and limitations of oblique parameter descriptions.

Findings

Electroweak measurement assumptions significantly affect the fit.

Dark photon models can evade traditional bounds when decaying into dark sectors.

Future LHC searches can probe parameter spaces relevant to these models.

Abstract

We examine how different assumptions about the hadronic vacuum polarization, the $W$ boson mass, and the forward-backward asymmetry in $b$-quarks at the $Z$ pole can impact the precision electroweak fit. We study the implications for a kinetically mixed dark photon, addressing the complementarity of precision bounds and direct searches, particularly in the case where the dark photon can decay into the dark sector, and we consider implications for future Large Hadron Collider searches. We comment on cases where the precision effects of the dark photon may not be well-described by the oblique parameters.