Light weakly coupled axial forces: models, constraints, and projections

Yonatan Kahn, Gordan Krnjaic, Siddharth Mishra-Sharma, Tim M.P. Tait

Research output: Contribution to journalArticlepeer-review

Abstract

We investigate the landscape of constraints on MeV-GeV scale, hidden U(1) forces with nonzero axial-vector couplings to Standard Model fermions. While the purely vector-coupled dark photon, which may arise from kinetic mixing, is a well-motivated scenario, several MeV-scale anomalies motivate a theory with axial couplings which can be UV-completed consistent with Standard Model gauge invariance. Moreover, existing constraints on dark photons depend on products of various combinations of axial and vector couplings, making it difficult to isolate the effects of axial couplings for particular flavors of SM fermions. We present a representative renormalizable, UV-complete model of a dark photon with adjustable axial and vector couplings, discuss its general features, and show how some UV constraints may be relaxed in a model with nonrenormalizable Yukawa couplings at the expense of fine-tuning. We survey the existing parameter space and the projected reach of planned experiments, briefly commenting on the relevance of the allowed parameter space to low-energy anomalies in π0 and 8Be decay.

Original languageEnglish (US)
Article number2
JournalJournal of High Energy Physics
Volume2017
Issue number5
DOIs
StatePublished - May 1 2017
Externally publishedYes

Keywords

  • Beyond Standard Model
  • Gauge Symmetry

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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